debugging XAMARIN forms apps doesnt always work - why? - visual-studio

I'm trying to finish a XAMARIN Forms project for a client and the whole time I've had issues. The biggest annoyance (really too many to list) is that when trying to debug using the iPhone simulator the debugger fails to hook up. Is there a trick I'm missing?
My setup:
I'm working on a Windows 10 workstation with a Mac Mini setup as my build server. I'm using Visual Studio 2017 Enterprise Edition. The Mac has the latest XCode and XAMARIN Studio stuff installed.
Everything is up to date
Right now the only 'solution' seems to be to stop the debugger in VS and start over.
Occasionally I have to close VS all together, reboot the mac and start from scratch.
Is there a trick? A checkbox somewhere that says "make this work like it should"?

1) are you in Debug mode on not Release ?
2) can you try on real iOS device ?
3) have you try on Xamarin Studio instead of Visual Studio ?
4) does it work on Android (simulator or real device) ?
5) have you try with a new clean project ? if it works try to remove bin & obj folders

Related

development app is deployed on IPhone, but I cannot start it

I have an app in Xamarin that I want to test on a physical IPhone (normally I test it on Android). I'm connected to a Mac, the development certificate is working and everything is deployed to the point that the app is actually installed on the IPhone itself. The issue however is that when I press the icon to start the app, it tries to start it and then is closes right after that (like it crashes or something).
I'm using Visual Studio for Windows, and it is stated that: "XAML Hot Reload encountered a problem and failed to start. Verify the Mono Interpreter for is enabled in the project settings, clean and rebuild the solution.". Mono Interpreter is enabled, I cleaned the solution and rebuild it multiple times. There are no errors given.
The app that is installed now shows the Xamarin icon and Xamarin splash screen (so not the custom one I designed). I don't mind that, but I'm not sure if that has something to do with this.
Does someone know what is wrong here and how to fix it?
Visual Studio for Windows version 17.4.1
iOS version 15.5
Note: this issue is only with the development and deployment directly from Visual Studio from Windows. When the app is distributed to the users (in App Center) the app works as it should.

Can't run a Xamarin App in iPhone Simulator from Visual Studio For Mac

In short: I am unable to run my app in the iPhone Simulator. There is no "Play button" (the triangle), only a Debugger button (hammer):
As you can see above I have "Generic Simulator". When I click on it, there is no list of various iPhones/iPads to choose from:
If I choose Android, I am able to run the app:
I have XCode installed. I ran XCode once.
I also installed the Command Line tools.
I created a new Xamarin Forms App:
Here are my iOS build options:
I am able to run the Simulator separately:
Creating an App in XCode and running in the Simulator works:
info.plist:
Prefrences -> SDK Locations -> Apple
Build -> Configurations:
Here is the kicker though. If I run a Xamarin App on my Windows machine using the iPhone Simulator on the Mac, it works!
What do I need to do so I can run my app inside the Simulator vis Visual Studio for Mac?
Few options you can worth to check. #WorldOfBasti suggested options plus following.
Configuration
Right click on the solution -> options -> Configurations -> Configuration manager -> ProjectName.iOS with Debug|iPhoneSimulator should be checked or if configuration "ProjectName.iOS with Debug|iPhoneSimulator" is not available then add this from General tab
Apple SDK path
Check Apple SDK path is set properly (Preference -> SDK Location -> Apple). It should have green tick mark with Xcode version and SDK path location.
Minimum system version (Deployment Target)
Change Deployment Target to minimum version (ie, lower than your simulator version)
Switch debug <-> release
Today I have also faced same issue which you are facing. I have switched debug to release, iOS to Android. Then reverted back to iOS and debug from the top device selection status bar. Then Simulator option was appearing. So, might be UI updated issue in Visual studio for mac. Please give a try.
I assume that you tried the basics things like restarting your Mac, etc. So here are a few things, that might solve your problem:
Check your build configurations, here is a good video
Close VS for Mac, start Xcode and create a test project which you run on a simulator. If it works try again in VS for Mac
Close VS for Mac, goto Xcode -> Preferences -> Accounts and download the manual profiles of your developer account. Try again in VS for Mac
Clean your project: In VS for Mac, goto Build -> Clean All. Then Close VS for Mac, goto your project folder and delete in "yourprojectname" and "yourprojectname".iOS all bin and obj folders. Try again
If all of this doesn't work, I would try to reinstall it (if you have any important projects, make a backup):
Uninstall VS for Mac and Xcode
Install Xcode again from the App Store
Install Visual Studio for Mac
Hopefully it works..
Looking at the Visual Studio for Mac logs, specifically the IDE log, I found this line ... 'The target name of simulated device could not be added because it's already cached'.
You are welcome to read through all of this ... but you may just want to go down to the Addendum 2 (final?) and see if that works for you ... it ends up being simpler and quicker than anything else I have found.
So, at first, I started clearing the cache with a 'xcrun simctl erase all' command from Terminal, and when I started Visual Studio for Mac I could run a Xamarin App, but launching the simulator took quite a bit of time.
So hare's something I found works that you might want to try ...
Close iOS Simulator on Mac (if any).
Close ALL copies of Visual Studio that are connected to the Mac ... either on the Mac itself or on another computer connected to the Mac (if any).
Start Visual Studio for Mac.
If you can't run a Xamarin App, Close Visual Studio for Mac.
Launch the Simulator manually (I have it in the Dock, so I just click it) ... wait for it to fully startup.
Now close the Simulator (from the Simulator menu).
Now restart Visual Studio for Mac.
If you still can't see the simulator devices to run on ... try the above steps one more time (this time you should only have to close Visual Studio for Mac followed by manually starting the Simulator, waiting for it to start, and then quitting the Simulator and finally restarting Visual Studio for Mac).
It still isn't great, but this has (so far) always worked for me. And the Simulator starts up substantially quicker then if I did a 'xcrun simctl erase all' command from Terminal.
Addendum: Most of the time the above works. But occasionally I still have to clear the cache from the Terminal with 'xcrun simctl erase all' command.
Also: I have also found (although maybe it's just my imagination) that clearing out the Visual Studio for Mac temporary .binlog files that are written in the 'T' folder will sometimes fix the problem (if you look at an IDE log from Visual Studio for Mac; right after the 'The target name of simulated device could not be added because it's already cached' message, you should see some .tmp files being created. The directory where they were created is the 'T' folder I'm talking about). I sometimes delete the tmp*.binlog and tmp*.tmp as a last ditch effort before using the 'xcrun simctl erase all' command to try to get back to where Visual Studio for Mac will see the iOS Simulator Devices.
Finally: This is really starting to feel like a bug in Visual Studio for Mac startup (or possibly during a iOS project load). The reason I say that is I can ALWAYS see the iOS Device list from Visual Studio for Windows (as long as I can connect to the Mac). In addition, I can leave Visual Studio for Mac running (even hidden) and test an app on the iOS Simulator from Windows, then, leaving the iOS Simulator Running on the Mac, run an App on Visual Studio for Mac. If there really were a 'caching issue' with the Simulator it seems to me I should have problems running anything on the Mac after using the iOS Simulator from Windows, but it always works. For now, I'm working on a single Xamarin Project on the Mac (and I don't use the Mac for anything else), So I just let Visual Studio for Mac 'open at login' (Dock setting) and automatically 'load previous solution on startup' (Visual Studio for Mac setting), hide Visual Studio for Mac (Dock Setting) and if I need it, Visual Studio for Mac is already loaded and able to see iOS Devices to run Apps on with a quick click on the Dock Icon.
Addendum 2 (final?): I have now found that if I just close a solution that I have open that shows 'Generic Simulator' and re-open it without exiting Visual Studio for Mac (sometimes I have to do it multiple times ... I think I've counted up to 5 times before it finally worked), it will start showing the device list and I can run the iOS app in the Simulator. I don't even have to close the Simulator if it's already running, which saves a bunch of time.
It still feels like a bug to me, I don't see why I would have to close/open a solution multiple times to get the iOS devices listed and be able to run an iOS app. What really gets me is if I reboot the Mac, don't open the Simulator and start Visual Studio for Mac, then open a solution, I still have to go through the close/re-open solution steps... sometimes more than once. The simulator is not set to auto start or anything like that. But, at least, it's getting simpler, and takes less time, to get to a point where I can run an iOS app.

Microsoft visual studio doesn't show any android emulator or physical device for Xamarin project

I have a xamarin project and i want to debug it, but visual studio doesn't show any emulator or physical device.
this is the menu
I wanted to restart adb from tools > android but it's disabled. but when I open a non xamarin project (for example a web porject) this options is enabled.
I can see my device in cmd with command adb devices and in android studio, every thing is fine and I can deploy some java application to my phone.
do you have Any idea?
Update
I created new project and in this new project, every thing is fine and I can debug with my phone or emulators.
but in my existing project which I'm currently working on, there is no device in list.
It happened to me just now using vs 2019, to fix this, manually remove obj and bin folders restart vs, and that's all :)

Xamarin Native iOS breakpoints not getting hit VS2017

I cannot hit a breakpoint in VS when debugging any native iOS app through VS2017 Pro. I have trawled the Xamarin/Stack forums and seen this has been a problem in the past and I have tried the suggestions but they relate to a 3.xxx version of Xamarin. Even an out-the-box new project untouched except for placing a breakpoint still does not hit, the build server pops up the simulator and runs as expected. Android is fine
This was working, I have recently downgraded from Enterprise to Pro but think this may be a red herring. I have 2015/13 pro installed with the same problem.
Is this an issue build server side or the windows side? I get the following generated in my bin App.app, App.exe, App.pdb but no app.mdb i do get the referenced dll.mdb files.
Current vs setup...
Microsoft Visual Studio Professional 2017 (2)
Version 15.1 (26403.7) Release
VisualStudio.15.Release/15.1.0+26403.7
Microsoft .NET Framework
Version 4.6.01586
Installed Version: Professional
...
Visual Studio Tools for Universal Windows Apps 15.0.26403.07
The Visual Studio Tools for Universal Windows apps allow you to build a single universal app experience that can reach every device running Windows 10: phone, tablet, PC, and more. It includes the Microsoft Windows 10 Software Development Kit.
Xamarin 4.4.0.34 (3f99c5a)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.
Xamarin.Android SDK 7.2.0.7 (b16fb82)
Xamarin.Android Reference Assemblies and MSBuild support.
Xamarin.iOS and Xamarin.Mac SDK 10.8.0.174 (7656cc6)
Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.
The Mac
Xamarin Studio 6.3
VS for Mac 7
See this similar answer: Xamarin iOS debugger not hitting breakpoints
Also, make sure you don't have a firewall blocking Port 10000.
I ran into something similar, and it turns out my debug settings for my physical device had some defaults that prevented debugging from working. This may not fix your issue, but you might want to at least check your project settings for a few things.
Under iOS Build I changed my Linker Behavior from Link All to Link Framework SDKs Only. Also, for some reason in a default debug profile, the Strip native debugging symbols option on that same page was checked. Make sure it's unchecked.
This one was already enabled for me but you should verify anyway: double check that on the page iOS Debug that Enable Debugging is checked.
I faced a similar issue but on Android application: I solved by uncheck the option "Code Optimization" from Project >> Options >> Build and set the DebugType to Full
Same here, windows 10, VS 2017 -> MAC -> iPhone
Somtimes I got Debug-Log and can hit breakpoints but mostly not.
A solution / workaround which at least works for me.
Problem:
Setup: Windows 10 with VS2017, Mac-Book, iPhone connected to Mac-Book.
Debug-Log / Breakpoint-Hitting seams to work sometimes (seldom) / non deterministic.
Solution / workaround:
Verify: In case no Debug-Log occurs (e.g. no "Loaded assembly:..." lines etc.) the "Choose Device" drop-down box in the "Tools >> iOS >> Device Log" window shows TWO times the name of the iOS-device.
Stop the debug and explicitly stop the app on the iOS-device (if necessary also delete it for re-deploy)
Via "Tools >> iOS >> Xamarin Agent" disconnect from your Mac and then reconnect again.
Verify: the "Choose Device" drop-down in the "Tools >> iOS >> Device Log" window now shows only ONE times the name of the iOS-device.
Debug the App - it now should work.
See also XamarinForum
Hope it also works for you.
Erdega

iOS app flashing and closing on remote debug from Visual Studio

I'm a beginner in iOS development in Visual Studio 2013 through Xamarin.
I made a test app and tried to debug it on the MacBook Pro through LAN remote debugging.
As soon as I debug, the app starts shows launch screen and after 1 second it close, this happens several times and then the app stops.
I'm using xamarin 6.1.4.1 on both machines.
It shows the error : An error occurred while executing the mtouch.
What should I do now??
After going through every things, I re-installed Xamarin Studio by using Xamarin Installer rather than installing individual components. Seems like Xamarin Installer makes some more changes in system other than installing components.

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