for loading only one image, 1st step is to drag a UIImageView to the screen.
Now I can assign an IBOutlet to it and load the image in code. And it adds the setImage=nil in viewDidUnload for me.
Or I can just use the utility panel to assign that image to the UIImage and write no code. But is this as efficient as that? Better? Worse?
How about assigning images to buttons? Is it better to assign them in code or just selecting the button's image from the utility panel?
It seems to me you are comparing doing something in interface builder to programatically, correct? They are both equally the same considering you use the same sort of memory management (nil out the ivar, etc.). Basically the xib does the exact same thing as coding it out when it comes down to it, it is just a matter of preference.
Related
I have an old app source code that uses storyboard & xib without auto layout or size classes. Even though I am rewriting it from scratch, it would take some time as number of modules are too many. The immediate need is to fix the code that manually sets frame of UI elements by detecting screen size at runtime. So a code written this way places elements outside the safe area:
self.controlBarBkg568h.frame = CGRectMake(0, CGRectGetHeight(self.view.bounds) - tapBarBackgroundImage.size.height, CGRectGetWidth(self.view.bounds), tapBarBackgroundImage.size.height);
Since there are so many interface elements that are placed this way, I am wondering what is an easy way to fix the code that works on iPhone X?
Use the safeAreaInsets property on UIView. This is a UIEdgeInsets object that describes the safe area for the current view. (Documentation)
In your specific case, you should be able to change your code to something like this:
self.controlBarBkg568h.frame = CGRectMake(0, CGRectGetHeight(self.view.bounds) - tapBarBackgroundImage.size.height - self.view.safeAreaInsets.bottom, CGRectGetWidth(self.view.bounds), tapBarBackgroundImage.size.height);
If you have many views positioned this way, you are going to have to edit them all to respect the safe area. This is one of the downsides of manual layout — it's hard to change in the future (especially if there aren't any helper layout variables where you can edit many variables at once).
More documentation about positioning content relative to the safe area is available here: https://developer.apple.com/documentation/uikit/uiview/positioning_content_relative_to_the_safe_area
First time building a user interface, had a few general questions
1) Does it really matter if you drag and drop view objects into view controller.. or if you programmatically add subviews and specify frames and fonts? What's the better approach to take?
2) In the programmatic approach, I end up guessing frame values, (x,y) points, and then checking in simulator if I like it. Is this the right approach, or are there faster, better ways to build out the UI? Maybe methods I'm not aware of?
3) Any useful tutorials/pointers in the right direction on how to get started?
Thanks!
1) Both approaches are fine, but the Interface Builder is usually better if you have a more static UI. In a more dynamic app (where views appear and disappear, or if you use UIViewController containment), you need to add/show/hide some of the views in the code. Even in that case you can design individual views in the IB, to make sure they look good, and then instantiate and display them in the code.
2) If you design your views in the IB, then the problem of guessing the sizes largely disappears. In some cases it can be useful to have an empty view added in the IB, which acts as a placeholder for your dynamic content. Then, when you add a view to it in the code, you just use the superview's dimensions so your view fills the placeholder.
I have been trying to create a simple swipe transition. However buttons seem immune to any CAAnimation that crops.
I am trying to get it so that a bar moves across the screen and as it goes over the button it removes the part it has just gone over.
I have tried bounds.width, size.x and many other key-value paths to achieve the affect but I haven't got what I wanted. It just relocates the text which always remains entirely visible
I have also tried changing the UIButton to a UIImage but the text does not seem to print on a UIImage.
I tried using masks too but I have heard they should be used as infrequently as possible as they consume the phones resources. I didn't really get very far with this either anyway as I hadn't used them much before.
I also tried placing it in a container view and then change the dimensions of that but again all of the text remained entirely visible.
I know I could have a view hide the button but I am trying to reveal the view behind as the bar swipes.
Does anyone have any suggestions of how to achieve a swipe transition on a UIButton?
Help would be much appreciated.
Thanks
I think what you're looking for really is a mask. See the tutorial here:
http://iosdevelopertips.com/cocoa/how-to-mask-an-image.html
What I'd do in your situation is create a custom UIButton class, and add a mask as in the tutorial, then animate the position of the mask. Slide the mask of, nothing shows. Slide it on, part shows until the whole thing is visible.
Edit: I haven't really heard anything about hogging resources, especially since it appears to be simple core graphics.
I am creating a Cocoa application wherein one view will contain the "hex dump" of the currently loaded document. Up until this point, I have been using a bog-standard (and very unappealing) NSTextField, but I am now looking for something more powerful.
I am a great fan of 0xED.app and would love to replicate its main "hex dump" view. How would I go about doing this?
I'm not necessarily after the eye-candy, but the ability to select a range of bytes without also selecting the offset or text columns. I am a loss as to where I would even begin to implement this effectively. Surely this is not drawn upon a blank canvas?
To get started and see how things basically work:
Subclass NSView.
Add an instance variable to hold your NSData.
Override drawRect:
Iterate your NSData
Use methods from NSString drawing AppKit additions to draw the bytes.
This approach will be slow for a large amount of data, but will give you a good handle on implementing a NSView subclass. After that, you'll want to improve the drawing performance by implementing something better than repeated calls to draw strings one at a time. You'll also want to implement overrides of methods like mouseDown: and keyDown: to handle input from the user to allow things like selecting a range of bytes.
That should get you started, once you have that going, I'd suggest asking follow up questions.
My guess is that it's probably accomplished using a NSTableView or subclass of it.
It might be a little tricky to get the correct text selection accomplished this way, but it's probably possible.
If you want to take a look at how a Cocoa interface is built you can use NibToXibConverter.
Download 0xED, right click on 0xED.app and select "Show Package Contents". Extract the Contents/Resources/English.lproj folder.
Run NibToXibConverter, browse to the folder extracted above, and put a tick next to "Decompile NIBs".
Select the "Convert" button and it will convert the NIBs to XIBs
Double click a XIB to open it in XCode and you can see how they are constructed
You will note that in the case of 0xED he is using a custom class (most likely a subclass of UIView with custom drawing as Jon Hess suggests).
I am trying to create a view for a kind of brainstorming application like, for example, OmniGraffle, with elements that contain textviews and can be dragged around. (Also, the should be connectable with arrows, but that is not (yet) the problem)
I did my homework and searched via google and read books about cocoa, but there seems to be no similar example around.
Since I am also new to cocoa, I’m a bit helpless here.
The thing I am sure of is, that I need a custom view in which I can create my elements - what I tried until now to do that is:
First, I searched for the syntax to add subwindows to a window to create my elements. Subwindows, I imagined, would automatically be movable and come to front and so on.
The problem: As the experienced Cocoa-programmers of you probably are not surprised, I was stunned to find nothing about anything like that - this seems to be something, that is just not intended in Cocoa?!
Then I thought about creating subviews that contain a custom view for the title bar drawing (where the user can click to drag the element) and a NSTextView.
Problems:
I read, that it is not so clever to create dozens of subviews in a window because that would be very slow (or would that be not so bad in this case because all the subviews would be instances of always the same class?).
Also I can’t find out how to load a subview from a nib- or xib-file. Would I need a viewController? Or would that make the dozens-of-instances-problem even worse?
And Apple tells you not to overlap subviews (okay, that would be not so important, but I really wonder how the guys at OmniGroup made OmniGraffle...)
Because of that, I now wanted to do the title-bar-drawing in the surrounding custom view and create the textview programmatically (as I understand, a text-“view“ ist not really a view and takes its functionality from NSCell to reduce all the effort with the views?).
Problems:
Even that failed because I was not able to create a textview that doesn’t fill the complete window (the initWithFrame: of the [[NSScrollView alloc] initWithFrame: aRect] just seems to be ignored or do I get that wrong?).
Also, there should be some buttons on each element in the final application. I imagine that would be easier to accomplish with a subview from a nib-file for each element?
Well, now that nothing works and the more I read, the more problems seem to occur, I am pretty confused and frustrated.
How could I realize such a program? Could someone please push me in the right direction?
I created a class for the draggable elements where I save position, size and text in instance variables. In my view, every new element instance is added to an array (for now, this works without a controller). The array is used to draw all the elements in a loop in drawRect:. For the text of the element I just use a NSTextFieldCell which is set to the saved text from every element in the same loop.
That way it is also possible to overlap the elements.