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There are three problems when using mtouch to launch an app in the simulator.
1.) mtouch fails to find mlaunch.
This is because it's installed in /Applications/Xamarin Studio.app/Contents/Resources/lib/monodevelop/AddIns/MonoDevelop.IPhone/mlaunch.app/Contents/MacOS/mlaunch
where mtouch fails to find it.
2.) The "--sdkroot=" argument is mandatory, not optional.
3.) The "--device=" argument is mandatory - omitting it omits in a crash when Xamarin.Launcher.Driver.LaunchSimulator() calls GetSimulatorDevice(null).
> 1.) mtouch fails to find mlaunch.
Fixed in PR 51
> 2.) The "--sdkroot=" argument is mandatory, not optional.
error MT0100: The option '--sdkroot' is required.
What makes you think it should not be required ? do we have out-of-date documentation somewhere ?
> 3.) The "--device=" argument is mandatory
Indeed, and it presently fails in a non-helpful way.
Failed to launch the simulator: Object reference not set to an instance of an object
error MT1008: Failed to launch the simulator: Object reference not set to an instance of an object
#2 is still unclear (about optional) but the help message was still mentioning a default of /Developer/ which is not correct (for both mtouch and mlauch).
That's fixed in (a second commit to) PR #51 (mtouch part + maccore/maciostools bumps)
#3 fixed in maciostools/master 67b20f63a69c53a126d3a9e1121345f8c5a920a9
Bumps in https://github.com/xamarin/xamarin-macios/pull/61
Fixed in xamarin-macios/master e726b5ab7e52bd7ece9db712d301ab5047e76560
I am not sure which build I can use to reproduce this issue.
I have checked this Issue with latest master build (XI 126.96.36.199)and observed that application getting launched on simulator using mtouch command. Below is my output:
Hello:bin 360_macmini$ ./mtouch -launchsim /Users/360_macmini/Desktop/Xamarin/HelloiOS/HelloiOS/bin/iPhoneSimulator/Debug/HelloiOS.app/
warning MT0061: No Xcode.app specified (using --sdkroot), using the system Xcode as reported by 'xcode-select --print-path': /Applications/Xcode.app/Contents/Developer
2016-07-01 14:06:28.346 mlaunch[1998:70396] Failed to wait for launchctl print process 2000: 10 No child processes
Please let me know if there is anything else I can check here.
For Item 1, I am not seeing such type of Issue with latest master build (XI 188.8.131.52) mentioned in comment#4
For Item 2, Gouri raised an issue in doc repository as per comment#6.
For item 3, It requires a maciostools/master bump and this fix is already included in XS master.