I'm a Windows (native, not .NET) programmer and I'd like to port an application to the Mac.
Actually, I believe it will be more of a rewrite, as the original depends on many activex controls.
As I have never used a Mac in my entire life, I'll need some guidance. O:-)
a) What book(s) would you recommend to make the move from Win32 to Mac OS?
b) Is there anything similar to Delphi (RAD) for the Mac?
c) Can anyone recommend (or not) Lispworks (www.lispworks.com)?
d) Is there anything similar to the Windows market of 3rd party COM components (so I don't have to write everything)?
e) Anything else I should be aware of the Mac market?
f) Oh, BTW, what Mac should I buy? O:-) (must be a laptop)
Thanks in advance
I've taught Cocoa programming to several Windows-experienced programmers. You may find a previous post on the subject useful.
Cocoa is a very different way of thinking then MFC and its kin. You will do much, much better if you take the time to learn how Cocoa approaches things and adapt to its mindset rather than trying to find the quickest way to implement your current way of thinking in ObjC. It is possible to write MFC-style code for Mac, but you will always be fighting the framework if you do. I've seen a lot of Windows developers struggle with this.
The best book to learn Cocoa is Cocoa Programming for Mac OS X. Assuming you are a C++ developer with a solid OOP background, this is the book to start with. If you have limited Object Oriented background, then start with Programming Objective-C 2.0.
You would be amazed how fast Objective-C can be to code once you understand the patterns. It really can be stunning compared to C++ in my experience. There are more RAD-like systems like REALbasic, and you can develop Cocoa apps in Ruby now which can be a bit quicker. But there really is no substitute in the Mac market for ObjC. It's hard to make an app that works like a Mac app without using the Mac frameworks, and Mac users tend to be much fussier about such things than Windows users.
I have no background in LispWorks, but LISP seems a terrible language for developing the kind of rich UIs that Mac apps are known for. I like LISP (quite a lot actually), but Functional Programming's "no side effects" philosophy seems at odds with most rich UI goals (especially as the Mac UI becomes more and more animation-centric). If anything, Mac programming is moving towards Declarative rather than Functional programming (Core Animation and Grand Central Dispatch have a lot of Declarative concepts creeping in).
There is not as large a third-party component market as there is for Windows. Some of this is because Cocoa already provides such a rich set of components, which MFC does not, and because well-behaved Mac apps are expected to use those components so that you work like all other Mac apps. There is definitely little market for commercial components in the vein of RadControls for .NET (very nice toolkit, that one). But there are quite a few nice free components out there with flexible licenses (generally MIT-based). A few of my favorites:
Positive Spin Media's excellent tabbar control
OmniGroup's frameworks (though I never use them "as is;" they're better used as examples of how to do things)
Growl
Sparkle
RegexKit
CocoaDev's ObjectLibrary list of other stuff
As I mentioned before, Mac users are picky about their UI. Much, much more so than Windows users. They expect things to be polished, and they expect things to integrate with all the little things that make Macs nice. That means drag-and-drop, Spotlight, services, Applescript, Expose, QuickLook, integrated spelling check, etc. etc. It's very hard to do all these things right if you don't use the built-in frameworks. That's why I recommend new Mac developers start at the beginning and learn the frameworks.
For a Mac, if you have a bunch of hardware lying around (like keyboards and monitors), then a Mac Mini is a nice cheap box. iMacs are great if you want an all-in-one, and any MacBook is appropriate if you like portability. There is no Mac on the market today that is not a perfectly fine development box. Obviously if you do a lot of work, an 8-core Mac Pro makes compiling much faster, but I've done a lot of professional development on a 13" MacBook. If you want to get in as cheaply as possible, look for refurbished or used (I love my refurbished Mac Mini). Any Intel-based Mac is going to be fine for development, at least while you're getting started.
If you are familiar with C, you may want to learn Objective C since that is the Macs "native" programming language. It's also what you have to use to write iPhone applications. Cocoa is Apple's primary API that will have a lot of the tools you are looking for.
a) Read this thread for book recommendations: https://stackoverflow.com/questions/7571/cocoa-and-objective-c-resources
b) Apple makes Xcode for developing in. There are certainly better ones out there, but it's not bad.
d) Cocoa is Apple's main API, which provides "core" services like CFNetwork for networking. There is also core data, core audio, core animation, core image, core location,... Underneath it all, OSX is Unix, so you have access to many unix/linux libs.
e) The iPhone is a big part of the Mac market. The iPhone and OSX development environments are not that different, so you can learn both.
f) Any Mac is sufficient for most development. If you want a laptop, it's really a question of screen size and price. But I would recommend at least a 15 inch screen. You don't need to spend extra for a faster CPU, but you may want to get a larger hard drive.
If you've done your native Windows programming in C and/or C++, you may have an easier time migrating your application to C#/.Net, and then running it in Mac using Mono. At least some of the available third-party .Net components will run on Mono (see http://www.mono-project.com/Third_Party_Controls_Status).
I have no idea what Mac you should buy - I recommend getting one of the pretty ones.
a) ...
b) You could use Python coupled with wxPython and be cross platform. Python is included by default with Mac OS X.
c) ...
d) I'm sure there is, but I can't tell you more. If you use Python, you get tons of third party libraries for free.
e) They don't take kindly alien GUI guidelines:
Word 6.0, launched in 1993, is widely considered to be the worst version of Word ever for the Mac, as it was based on the same codebase as Word 6.0 for Windows. That meant that it looked and worked more like Windows software than a Macintosh program. Mac users were so up in arms that Microsoft actually released a Word 5.1 downgrade to unhappy Word 6.0 owners.
f) Mostly any iMac will be good enough for programming. Choose the one that you like the most and has lots of RAM.
e) Its a small market.
f) An iMac. Edit: since it says laptop - Macbook Pro 13 is a great deal.
Related
I'm starting to program. Already did some things with Java: a calculator, one document management system powered with a database and some other home projects. But I don't like the visual look. I love however how mi Mac's Apps look. And I want to create Apps for mac. Already buy one but when I open netbeans to program it looks like the Apps doesn't feel like mac.
Is there any specific java code to make the controls looks like how the other mac apps look? My dad mention something about Object C but I don't understand. Can someone please explain me.
AFAIK You'll never get the look and feel of Aqua (Mac's UI Kit) by using Java. Why? Because to make Java platform independent some things needs to get ripped off. And native controls are one of them.
I think you're taking about Objective C which is the native development language for building Mac Apps. I'll recommend you the book "Learn Objective-C on the Mac" is pretty useful.
P.S. I'll encourage you to start with iOS (iPhone and iPad apps). Why? Well, I think is easier to begin with. Things like fixed resolution and so on make your development efforts small while beginning with. (Just my 2 cents)
If you want to code in Objective-C, you'll first need to trek over to the App Store and download Xcode. This will install C/C++/Objective-C compilers on your Mac and then you can start getting your hands dirty.
Depending on what you are trying to accomplish, you can just google/read/learn and build your own frameworks from the ground up or look at something like Cocoa to get started as well.
http://developer.apple.com/technologies/mac/cocoa.html
Cocoa Frameworks
The Cocoa frameworks consist of libraries, APIs, and runtimes that form the development layer for all of Mac OS X. By developing with Cocoa, you will be creating applications the same way Mac OS X itself is created. Your application will automatically inherit the great behaviors and appearances of Mac OS X, with full access to the underlying power of the UNIX operating system. Using Cocoa with the Xcode IDE is simply the best way to create native Mac applications.
Good luck!
Apple has deprecated a lot of the Java support in OS X. It's possible to have a Java application integrated, but there are some annoying bits missing. See one of my questions demonstrating some issues with Java applications in the Dock. You would be better off using Objective-C instead, since Apple has lots of documentation and tutorials available.
You're thinking of Objective C. You can also do applications for Mac using C/C++ but as of late the "popular" language for Mac development is Objective-C. There are tons of tutorials and plenty of documentation to walk you through writing apps for both Mac and iOS.
Well, simple situation. I happen to be a software engineer who uses mostly Delphi and C# for software development. Delphi is great for desktop applications while C# is ideal combined with ASP.NET for web applications. However, I am considering to teach myself more about software development for the Mac. Xcode and Cocoa would be the environments to start with. Learning new languages is no problem for me!
However, before starting to write code on a Mac, I first need to buy one and they're reasonable expensive so buying one is a decision that will take me a few months before I know which one I need. So, to help me right now, I would like to know the possibilities that I have to learn more about Mac development without the need for a Mac!
For example, does OS X work in a VMWare environment? Are the development tools also available for Windows? Is there a clear API overview of the OS X libraries?
Or should I first buy a Mac, play with it for a few weeks and then decide on how to develop software for it? In other words, should I start spending now, or in a few months? :-)
Perhaps a macmini would be the best bet but failing that:
MacOSX in VMWare: http://wiki.osx86project.org/wiki/index.php/Vmware_how_to
Development tools for windows? I'd stick to XCode as it can compile multi-binary apps.
Here's the clearest overview I can think of: http://developer.apple.com/referencelibrary/MacOSX/index.html
Hope this helps!
Mac OS X works in a VMWare...
Unfortunately XCode works only on Mac OS...
There are versions of Max OS, which runs on x86 machines. You can avoid buying a Mac PC, but you have to pay for the OS and XCode...
EDIT: Xcode is free
You definitely want a Mac if you want to develop for the Mac. Even Java requires local testing.
That said, Macs are not very expensive and run Windows too.
If you want to learn and start programming before you have a Mac, I recommend either Java or .NET, specifically Delphi Prism.
See here my own first experiment with Delphi prism:
http://leaukiprog.blogspot.com/2009/07/delphi-prism-first-experiment.html
You can write a program for Windows, keep GUI code and other code separate and later replace the Winforms GUI with a native Cocoa GUI on the Mac.
I found that Pascal is a good language for accessing native APIs from .NET. Everything looks cleaner than with C#, I think.
The new version of Delphi Prism is coming out on the 25th, as far as I know.
You might also look into the GNUstep project. This will let you experience objective-c a little bit before you make the plunge, albeit with the GNU libs instead of cocoa.
Good Mac (or iPhone) software is an artisan product; it reflects the culture and tastes of Mac (or iPhone) users. Because the Mac is a premium platform, users tend to be more sensitive to the feel and polish of the apps. Thus to successfully program for the Mac/iPhone or even grok the Cocoa frameworks properly, you have to grok the Mac user experience. Although many coming from the Windows or other-UNIX world try to skip this step, they do so at their own peril.
So, as a Mac developer (who also writes for other UNIX OSes), my recommendation is buy a Mac and start using it, full time if you can. A Mac Mini is completely adequate for development and will set you back only a few hundered dollars, including the OS. Consider that on Windows, this is often less than the price of a full VS license. Everything else (Xcode, libraries, etc.) are free.
Once you have a Mac and begin to grok the feel of things, you'll discover that there are a number of development options. Besides the Cocoa frameworks--which can be used from Python (via the built-in PyObjC bridge), Ruby (via MacRuby or RubyCocoa)—-there are a number of other options. Qt from Nokia and Mono are viable. Often cross-platform apps written in Qt or Mono are disliked on the Mac because they don't feel "native" (see above), but really the problem is not the framework. If you get the Mac user experience you can write a very passable Mac app in a cross platform framework. You just have to intend to write a Mac app, not get a Windows app working on the Mac.
If you code in RealBasic or Lazarus, you can run and compile your apps for both Mac OS and Windows (and Linux in the case of Lazarus). RealBasic isn't that popular outside of the Mac Platform, and isn't free. Lazarus is still a little rough around the edges, but is basically a free version of Delphi.
Lazarus is working hard on a native COCOA port with the next major version of FPC (though that will probably be available only in 2011)
Macs use Objective C. The APIs are very useful and there are many tutorials online. You'll be using Xcode, the Mac equivalent to Windows' Visual Studio and Linux's Glade.
I love making cross-platform applications. In a few hours I can prototype an application in Mac and publish it online. Then it'll take a day or two to port to Windows.
A Mac looks expensive, but it's not if you look what you get for your money.
It is entierly up to you if you buy one or not. I guarantee you'll have a lot fun with it, next to programming. If you want a cheap Mac, just buy a Mac Mini for 500 dollars, which you can connect to the Display you already own.
I recommend doing this on Mac OS X rather than Windows, but again: it's up to you.
P.S. You can use VMWare, but I think it's slow if you have less then 4 GB RAM.
A Mac really isn't that expensive if you go down the second hand route, I was put off by the price of brand new Macbooks so I got a late 2007 model for £350 and added an extra gig of RAM to it.
Reasonably priced, less hassle for development as well!
If you want to have just a general feeling about ObjC and the object libraries, why not giving a try to GNUStep?
Take a look at it here:
http://wiki.gnustep.org/index.php/Main_Page
I see that more and more are using Macs for development.
Why is this? What advantages does the mac have?
Except for the obvious Microsoft languages, are there any that are not suitable for the mac?
And last, what is a recommended, not so pricey macbook for programming (C++, Java, Ruby, Haskell etc.)?
A mac is Unix based and more user friendly than most Linux distrib. They also have a nice set of software. Another reason could be that you can only develop for iphone on a mac (objective C).
I've been developing with a Mac for the past 4 years and never ran into issues (or at least, not more issues than on a PC). I've been developing in Ruby, PHP, C, C++, Ada, Java... I think that all the languages will work just fine, aside from Microsoft technologies such as .NET... but then you can get parallels, VMWare or bootcamp to bypass this.
You can get a Macbook for 1000$... it's still expensive, but totally worth it.
(source: akamai.net)
I already answered a bit to this question here.
The Mac is also very nice for web development. It is very easy to set up a local development environment as PHP, MySQL (I think; if not there's an easy installer), and Apache come preinstalled. There is a lot of nice web development software for the Mac, such as Coda, CSSEdit, and TextMate.
As for software:
C++: Use Xcode. It's quite nice (though I hear it won't win many converts from Visual Studio. Having never used VS I can't comment on that).
Java: Use Eclipse. But then, you probably already knew that.
Ruby/Haskell: Textmate!
Also, for GHC, install MacPorts and use that to install your haskell compiler.
Lastly, don't pay Apple's prices for RAM upgrades. You can buy standard RAM from any supplier for much less.
Any currently shipping Macintosh will be adequate for development (Mac Mini, Low end MacBook Pro) if you are a hobbyist or have small projects.
I find a 2.53Ghz MacBook Pro fine for my weekend projects, iPhone development and script hacking. For my Day job I'd have a hard time getting by with less than a top end Mac Pro with much less modest specs.
I do .NET development regularly on my macbook pro using Parallels. The performance hit is noticeable but not enough to matter most of the time. The worst part for me is the inconsistency in moving the cursor around in applications using the keyboard (CMD + left/right, etc). I don't know if it's from me messing around with Parallels keyboard binding settings or not, but even after 6 months, I still don't know the different shortcuts as well as I do in Windows.
Mac is intensely used by designers with photoshop, ilustrator or after effects.
Also there are more and more objective c programmers which develop iphone apps.
I believe that because the only eligible way to create iphone apps is to own a mac, developers were forced somehow to buy mac in their way to create apps.
my background: i've been developing web applications using php and javascript for the past ten years. before that, i've developed applications using turbo pascal for DOS. in my opinion application and web application development are two different kinds of development (at least it's what i think when i remember back the old days of DOS application development).
now i am in the need to go back to "normal" application development for various reasons. the application i want to build needs a GUI and it has to run on osx and windows. as mac os user it would be very nice for me to get an application as result, that really feels like an osx application. i don't need any special UI components: an explorer/finder like tree, a datagrid and some form-elements would be enough for my needs.
now the problem is, that i don't know where to start: i would classify me as newbie, because it's that long time since i last developed anything other than a web application. are there any recommendations of programming languages and gui toolkits with a not to steep learning curve? or can you recommend any book i should read for getting into cross-plattform osx/windows app development?
many thanks!
thanks everyone! i think i'll have a look at realbasic!
Edit Nov 2011 - a retraction
Most of what I say below is still true however I have now got serious reservations about recommending REALbasic for anyone trying to release commercial-quality applications. To save me remembering to edit this post later, see if RealSoftware have managed to release a robust version of their IDE using the Cocoa version of their frameworks. If not, be very cautious.
It's with a heavy heart that I write this because I still really like the language and think the framework and IDE are well-done. The problem is apparently one of under-capitalization and possibly a software development culture inside the company that consistently fails to deal with a bug regression problem. Many bugs are fixed each release but there appears to be a huge tax on the developers in the number of introduced bugs. They have a very small team for the complexity of the product, especially considering the newly released Web Edition which is effectively an entirely new platform.
It's still theoretically a great product but take advantage of the trial period, test it thoroughly on each of the platforms you plan to target and decide if you can live with any bugs you find because they may be there for a while.
REALbasic.
The language is a powerful, modern OO language that won't be hard for you to adapt to from your vaguely remembered Pascal or current JavaScript. It has most of the power of C++ without the dangerous bits that make debugging a nightmare. You will also find the IDE simpler and easier to deal with than say Visual Studio.
The IDE makes it very easy to throw together a GUI and have it just work on multiple platforms. The Pro version has one of the best cross-platform debuggers I've used and it is easy to just work (say) on a Mac and develop for Windows and Linux, compiling and testing with one click.
There is also a thriving community including many people at your level of expertise so you won't be mocked for being a newbie.
I am a professional software developer with over 25 years experience and currently mainly working in REALbasic, C++, C#, Objective-C and a bit of Ruby. For apps such as you mention, REALbasic is my tool of choice.
edit: I can't believe someone downvoted this but didn't have the guts to add a comment explaining why. I'd heard about prejudice against REALbasic but this is the first time I've encountered it. In what way was my answer inappropriate for this question?
Just to add to my cred, I've implemented cross-platform frameworks used by systems deployed to tens of thousands of end users - I have the C++ cross-platform experience to applaud someone else doing a good job and the REALbasic frameworks are very nice.
The best cross-platform tool I've dabbled in with a relatively small learning curve...especially if you're familiar with Visual Basic...is REALbasic. With REALbasic Pro you can compile a program to target Win32, Linux, and OS X from the same codebase, as long as you're not using OS-specific calls and features (which you can do with plugins or direct calls). Their support has been pretty responsive to my questions, the personal edition (which compiles to only the single target platform you'd downloaded the IDE for) is free for Linux and inexpensive for other platforms, but really you might want to download and try it out. One IDE, relatively inexpensive, and can compile native applications on OS X, Windows, and Linux...it's less hassle, and for me that's important when you want to get a job done.
I'd advise against C and Qt and would also recommend REALbasic.
With your background in Pascal and probably JavaScript you'll feel much more comfortable with REALbasic. I've done a lot of coding in Pascal and C/C++ - where Pascal guides you to avoid programming mistakes, C lets you step right in, even invites you, and then you'll have a hard time figuring out why it went wrong. Qt is a very abstract framework and requires you to learn a lot before you can get something working, just like with C. When compared to the easyness we used to have with TP back then.
RB is much more like Pascal in this regard. And its IDE is quite modern in regards to supporting your programming, with an easy-to-use GUI designer, straight-forward editor to fill in the gaps for handling UI events, code completion, etc.
Only when you get into huge program sizes, RB loses some of its appeal because it is missing tools to give you a good overview of complex class interactions etc.
Another thing is that Qt is more likely to cause ugly-looking Mac apps than RB would. RB visually guides you to get it all aligned nicely - in Qt you have to work with numbers, offsets, etc. to position your objects (at least it was that way when I used Qt 2 years ago).
I've written quite a few x-platform apps in RB and am pretty happy with the results.
You won't probably write those super-nice looking apps that compete with the best on the open small business market, but if you just want to get some solid code working, with an easy-to-design UI that's acceptable to the average user, give RB a try.
It's not free, though. But its rather small community is on your side - they're eager to help, instead of bashing everyone who's trying to talk sense :)
I'm new here but picked up on this thread through the REALbasic User Group. I think my position was similar to yours. I did website design for my work, using mostly javascript (with a little php, not much). I had a Pascal and BASIC background. I'd dabbled it C but didn't like the level of detail you needed to monitor it. It reminded me too much of assembly (which I still have nightmares about from my high-school/college days).
I was looking for a cross-platform language, with a familiar feel to it, but initially started with VB because it was free. I prefer programming in MacOS however, so I tried REALbasic. I found that REALbasic's UI builder was much easier to use than VB's. I'd echo other comments that the community is the most responsive of any user groups I've been involved with. I've since used REALbasic and my Mac to make several programs that over 100 users use every day at my work (on PCs, mostly XP and 2000). I've received compliments on the polish and ease of use of these programs. You DO have to remember to adjust the 'little' things to make it look right cross platform (ie: default button placement is opposite on PC vs. Mac, button sizes are different on Linux, etc). Many people have donated custom classes that do this stuff for you though.
People seem to assume that a "BASIC" language cannot be powerful enough for their purposes. While it is BASIC at it's core (with For..Next, Do..While, and If..Then commands), it ain't your daddy's BASIC. It's much more OOP than anything else I've used, based upon an event-driven structure, which for me was easy to pick up. They have a free trial, so grab a demo and run through the tutorial. If you get stuck, ask for questions on the NUG or Forums at the website and you'll likely get an answer quickly.
You may be interested in the following questions and answers:
Cross-platform development - Go with a cross-platform UI toolkit or native on multiple platforms?
Easiest cross platform widget toolkit?
Should I use a cross-platform GUI-toolkit or rely on the native ones?
Using a Mac for cross platform development?
and many others suggested in the Related sidebar of these questions.
Some answers suggest gtk (which is used by cross-platform gimp). Others suggest native approaches. Some suggest that a Mac is a nice platform for developing for Mac OS X, Windows, Unix and Linux.
I wholeheartedly recommend RealBasic too. I have been using RB for about 8 years now and find it to be a perfect tool for my Companies development needs, from small apps, to large multi-user systems.
It is perfect for beginners and those that are getting back into programming, and also for professional developers.
Highly recommended.
As Andy Dent and others here have indicated, for a newbie to create cross-platform applications it is hard to beat REALbasic (now Xojo).
Sure, there are plenty of other cross platform solutions such as QT (C++), Java, .NET (to some extent) and wxWidgets but they are not something a beginner would be able to use effectively.
I have many years of professional development experience in a wide variety of languages and technologies and I prefer to use REALbasic most of the time.
With that said, you might also consider Runtime Revolution or Adobe Air.
Whilst it might seem tempting to use a language thats platform independent and allow you to write the app once and use anywhere, you will undoubtably be sacrificing something on each, particularly in the UI and user experience.
If you can your best creating something using a native API that lets you take full advantage of the features of the OS to make your application shine.
I would definitely go for C++ and Qt, the code you write once will compile and run without problems on Windows, Mac and Linux. The new IDE that comes with Qt - Qt Creator is brilliant, works and looks the same on Windows, Mac and Linux, you don't need to anything else to start writing cross-platform applications.
I tried WxWidgets but didn't find good IDE, the best one was Code Blocks but GUI Designer is not perfect and has different problems on different systems and the IDE itself is still under heavy development.
Other options are Java and C# but those are not cross-platform languages, those are platforms themselves. Although you wouldn't need to compile code for each platform there will a lot of different issues on the way...
If your GUI's simple enough, why not just create a generic GUI layer, then program to that? Compile a version for each OS using native widgets. That's the best way to ensure native L&F on multiple platforms.
Both the Qt and REALbasic suggestions are good, although they tie you to that particular technology (which I can't imagine would be an issue in this particular case).
Personally, I'd go with Java, because it's worked for me before (I had an app that ran on my PDA, my phone and my desktop), but it doesn't use native widgets.
Adding a late comment here:
Take a look at Revolution. It's sort of like a modern Hyper-card on roids. And it's cross platform (Mac, Linux and Windows). This is a serious competitor to RealBasic and is coming on strong. Though I still use RB (and like it) I'm giving Revolution a serious look at.
I would also look into either Realbasic or Revolution. They both create cross platform native apps. Personally I think Realbasic would be a better choice as it is very similar, language wise, to VB. You can learn some valuable skills with RB and it can grow with your experience. I have been using VB and RB for more then 10 years combined and I think you will be happy.
If you need your code to be cross platform, you would have to go with something like QT.
Although, I would recommend using native API for each one (Cocoa for Mac OS X, .NET or the Win32 API for Windows). User experience will be much better. But of course, that will cost you more money in terms of developers hours.
In the wikipedia article on Cocoa it says:
There are also open source implementations of major parts of the Cocoa framework that allows cross-platform (including Microsoft Windows) Cocoa application development, such as GNUstep, Cappuccino, and Cocotron.
Yet when I looked into whether Mac application Tweetie was available for windows the developer had ruled it out:
Windows doesn't have Cocoa, the programming environment that Tweetie is made in, as such, it seems like a poor possibility.
I'd like to have an answer to point the Tweetie developers (and as a resource for other cocoa developers) which would tell them:
Which implementation is the most suitable for getting a cocoa app running on windows?
How much work is it likely to take to get the app running under windows?
How easy/hard is it to maintain a common code base for Mac and Windows?
(any other considerations I've missed?)
Of course if it would be too much work I'd like to know that too before suggesting it and potentially sending someone else on a fruitless search.
Don't forget:
“Major parts of the Cocoa frameworks” is not the same as “the entirety of the Cocoa frameworks”. Tweetie could be using something that's missing.
Tweetie could be (very probably is) using APIs from the non-Cocoa frameworks, such as Core Foundation, Core Services, Core Graphics, and Core Animation. A port of the Cocoa frameworks alone won't include any of these APIs, and even a more complete Mac-API-emulation framework will not include all of them.
These frameworks are eternally chasing Apple. Even if they catch up, they'll be instantly behind again as of the next Mac OS X release. Mac developers already put off using new APIs in new Mac OS X releases while they wait for users to upgrade to those new releases; now you're asking atebits to also wait for the other-framework developer to catch up to Apple again.
Any second implementation of an existing API will have bugs that the first implementation doesn't, and vice versa. These differences will cause development and support problems.
You're asking atebits to add a third platform to an application that already exists on two. Supporting one platform is a lot of work. Supporting two platforms is a hell of a lot of work. Supporting three? Now you're getting into big-company territory.
So, even with these Cocoa-like frameworks, the answer is: Hard.
Among GNUstep, Cappuccino and Cocotron, Cocotron is only possible choice to port a Mac application to windows.
Cappuccino is for web and GNUstep only runs on top of cygwin or mingw, which means the GUI looks nothing like native windows apps.
It is theoretically possible to build cocoa windows apps using Cocotron. However, the reality is that it is still very hard to use, and it is still quite limited in the Cocoa API.
Therefore, two possible solutions:
Try hard to remove the codes that are not supported by Cocotron in the original code base and do the cross compilation. Maintaining common code base will be painful.
Start a new GUI at all, no common code base. two choices here
Start a cross platform project with cross application framework such as Qt, or Java.
Start a windows only project. There are a lot of choices here, .Net WinForm application, MFC, etc.
There are Windows compilers for Objective-C (the programming language used to write cocoa apps). However, Cocoa includes the frameworks for presenting the GUI. These visual frameworks are specific to Mac OS X because they use OS X only windows and other controls. So someone would need to re-implement the controls in Cocoa to use Windows controls.
Also, I am fairly certain that Tweetie uses Mac OS X only technologies like Core Animation. This does not exist on Windows, so the nice animation effects present in the apps would have to be implemented in a completely different way.