Figure out 'dotnet run' CLI experience for iOS and Android

[jonathanpeppers]

CLI experience

If you try the samples here, you can run iOS/Android projects at the command-line with:

$ dotnet build HelloAndroid.csproj -t:Run
$ dotnet build HelloiOS.csproj -t:Run
$ dotnet run --project HelloAndroid.csproj

iOS behavior

iOS launches the first simulator it finds in the list (which is currently an iPad) and prints the iOS console output at the command-line and blocks. You have to Ctrl+C to get the dotnet command to exit. You get an MSBuild error message after hitting Ctrl+C.

@rolfbjarne feel free to chime in 😄, there might be a way to select which simulator you want.

Android behavior

Android uses the existing adb connection along with the AdbTarget property if you need to select which device/emulator to use when there are multiple. The dotnet command exits successfully when the app is launched, giving no console output for the app.

The Xamarin.Android SDK does not have any logic for locating emulators and launching them from MSBuild, as the IDEs do this for Android, currently. There is not any logic for giving adb logcat (console) output either.

Can you dotnet run apps? Like .apk, .aab, .app, or .ipa files?

There does not currently seem to be a way to do something like:

$ dotnet run bin/Debug/HelloAndroid.apk
$ dotnet run bin/Debug/HelloiOS.app

I think we would need some new behavior for the dotnet run command for this to be possible. --project runs MSBuild, so that is why we were able to get this part to work.

Conclusion

What should the behavior be here? Both iOS/Android behaviors are reasonable in their own way.

[rolfbjarne]

@rolfbjarne feel free to chime in 😄, there might be a way to select which simulator you want.

Yes, there is a way, but it's not very user-friendly at the moment.

1. Use /Applications/Xcode.app/Contents/Developer/usr/bin/simctl list to get a list of all the simulators.

2. Choose one, and copy the corresponding UDID.

3. Set the _DeviceName property like this to select the simulator:

    dotnet build -t:Run /p:_DeviceName=:v2:udid=<UDID>
   

You have to Ctrl+C to get the dotnet command to exit.

You can hit Enter to terminate the app.

[Silic0nS0ldier]

Thoughts from a stranger on the internet;

• Try to match existing dotnet CLI conventions. Deviations (even to match established Xamarin specific conventions) should be avoided to keep everything idiomatic.
• The dotnet CLI run semantics lean more towards running on the current device (local machine). With iOS and Android app development, I think this needs to be addressed. A new flag to explicitly specify what device to deploy to may address this (ideally this would not be Xamarin specific, realistically there is no reason for it to be long-term).
• dotnet run target device discovery should be easy. Scenarios like connecting to a MacOS agent complicate this somewhat as ideally the connection should stay open during development (being a slow resource to prepare after all). It may be necessary delegate responsibility elsewhere to avoid creating a difficult to debug black-box, given the number of moving parts here.

As for the commands and their expected outcomes...

dotnet build

Builds a project and all of its dependencies.

IMO under existing dotnet CLI behaviour this doesn't need to produce an app package, just something that can be run (there are ways to get code running on a target without needing something link an APK, handy for alternative deploy approaches like a certain now dead Xamarin debug app).

A noted behaviour with Android deploys however is that it dumps an APK in bin. In a CLI setting where a more customised workflow might be at play, it may be preferrable to at the very least expose a switch to do this up front. Though such behaviour could still be delegated to dotnet publish.

dotnet run

Runs source code without any explicit compile or launch commands.

There are 3 ways I've used this command.

1. dotnet run in project directory, to run said project
2. dotnet run ./somepath/some.csproj to run a specific project
3. dotnet run ./somepath/some.dll to run a specific assembly (be interesting if this could somehow be mapped to dotnet build outputs with this new target platforms)

[richlander]

@Silic0nS0ldier Good feedback, but I'm pretty sure that the experience that @rolfbjarne raises is very much an "at the moment" sort of issue. We'll get this sorted, and it will end up being very similar to what you've written.

IMO under existing dotnet CLI behaviour this doesn't need to produce an app package, just something that can be run

I like this. Yes, the key task of dotnet build should be creating runnable assets that will run in a well-defined environment.

[balbarak]

What about that, you should specify emulator or target device when you call dotnet run for iOS or Android

If there is no target device it should failed to run

Ex
dotnet run -t emulatorname

[Thibaultce]

@rolfbjarne feel free to chime in 😄, there might be a way to select which simulator you want.

Yes, there is a way, but it's not very user-friendly at the moment.

1. Use /Applications/Xcode.app/Contents/Developer/usr/bin/simctl list to get a list of all the simulators.
2. Choose one, and copy the corresponding UDID.
3. Set the _DeviceName property like this to select the simulator:

    dotnet build -t:Run /p:_DeviceName=:v2:udid=<UDID>
   

You have to Ctrl+C to get the dotnet command to exit.

You can hit Enter to terminate the app.

Thanks for the tip, it works like a charm with the emulators.
But I'm not able to use the dotnet build command with an actual device. Is the call different ? I tried to replace the UDID by the UDID of the IPhone connected.

[rolfbjarne]

But I'm not able to use the dotnet build command with an actual device. Is the call different ? I tried to replace the UDID by the UDID of the IPhone connected.

Try doing this for device:

dotnet build -t:Run /p:_DeviceName=<UDID>

if that doesn't work, please show the output.

[Thibaultce]

It's working, thanks !

[PureWeen]

msbuild.binlog.zip
@rolfbjarne I'm trying to launch our maui samples to a physical device but it's just failing with the attached exceptions

https://github.com/dotnet/maui/blob/main/src/Controls/samples/Controls.Sample.iOS/Maui.Controls.Sample.iOS-net6.csproj

[rolfbjarne]

msbuild.binlog.zip
@rolfbjarne I'm trying to launch our maui samples to a physical device but it's just failing with the attached exceptions

https://github.com/dotnet/maui/blob/main/src/Controls/samples/Controls.Sample.iOS/Maui.Controls.Sample.iOS-net6.csproj

I believe you can work around that by executing this locally:

sudo chmod a+x /usr/local/share/dotnet/packs/Microsoft.NETCore.App.Runtime.AOT.osx-x64.Cross.ios-arm64/6.0.0-preview.6.21352.12/Sdk/../tools/mono-aot-cross

This is already fixed, and the problem should go away in a future preview (not sure if it'll be in preview7 or rc1).

[tmarkovski]

But I'm not able to use the dotnet build command with an actual device. Is the call different ? I tried to replace the UDID by the UDID of the IPhone connected.

Try doing this for device:

dotnet build -t:Run /p:_DeviceName=<UDID>

if that doesn't work, please show the output.

Using net6.0 (6.0.100) this command doesn't work.

EXEC : error MT1212: Failed to create a simulator where type = iPhone 4s (com.apple.CoreSimulator.SimDeviceType.iPhone-4s) and runtime = iOS 15.0 (15.0 - 19A339) - com.apple.CoreSimulator.SimRuntime.iOS-15-0. [/Users/tomislav/Git/DELETEME/tfmtest/ButtonDemos/ButtonDemos.csproj]
          
/usr/local/share/dotnet/sdk/6.0.100/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(897,5): error MSB3073: The command "/usr/local/share/dotnet/packs/Microsoft.iOS.Sdk/15.0.101-preview.10.251/tools/bin/mlaunch --launchsim bin/Debug/net6.0-ios/iossimulator-x64/ButtonDemos.app/ --device 12214EEA-4CC2-4C4B-A0C3-A52153C32249 --stdout /dev/ttys003 --stderr /dev/ttys003 --wait-for-exit" exited with code 1. [/Users/tomislav/Git/DELETEME/tfmtest/ButtonDemos/ButtonDemos.csproj]

Specifying it as /p:_DeviceName=:v2:udid=<UDID> does work.

[hflexgrig]

I'm getting

/usr/local/share/dotnet/packs/Microsoft.iOS.Sdk/15.0.101-preview.12.710/targets/Xamarin.Shared.Sdk.targets(1244,3): error MSB4044: The "GetMlaunchArguments" task was not given a value for the required parameter "AppBundlePath". [/Users/haykgrigoryan/RiderProjects/MauiApp1Silicon/MauiApp1Silicon/MauiApp1Silicon.csproj]

When runninng

dotnet build -t:RUN -f net6.0-ios

Any ideas how can I make MAUI app run on IOS device on my M1 mac ?

[rolfbjarne]

@hflexgrig can you try getting a binlog (by passing -bl: dotnet build -t:Run -f net6.0-ios -bl:msbuild.binlog), and then attaching that binlog here?

[lhughey]

What worked for me on Mac targeting iOS is this.
dotnet build -t:Run -f net6.0-ios /p:_DeviceName=:v2:udid=362528C6-A6A2-4A39-A630-420D714C4A3D

The '-f net6.0-ios' part was necessary