Azure DevOps Build Xamarin.IOS with IOS 12 as target - xamarin.ios

Question

I have an Application written with Xamarin and a buildpipline on Azure Devops. This builds fine when I target IOS 11.x. However I would like to update to SDK 12 since Apple starts to enforce this starting in march 2019:
SDK Version Issue - This app was built with the iOS 11.4 SDK. Starting
March 2019, all iOS apps submitted to the App Store must be built with
the iOS 12.1 SDK or later, included in Xcode 10.1 or later.
But when I build I always get this error in my Azure Devops pipeline:
MTOUCH : error MT0074: Xamarin.iOS 11.14.0 does not support a deployment target of 12.0 for iOS (the maximum is 11.4). Please select an older deployment target in your project's Info.plist or upgrade to a newer version of Xamarin.iOS.
Based on this article I tried to set the SDK Version with this script:
/bin/bash -c "sudo $AGENT_HOMEDIRECTORY/scripts/select-xamarin-sdk.sh 5_12_0"
Unfortunately it still uses the 11 SDK instead of 12.
Did I choose the wrong Mono Version or is that the wrong approach to select the Xamarin.IOS SDK?
My complete build YAML for the IOS Job:
queue:
name: Hosted macOS
demands:
- xcode
- Xamarin.iOS
steps:
- bash: |
echo "Select Xamarin Version"
/bin/bash -c "sudo $AGENT_HOMEDIRECTORY/scripts/select-xamarin-sdk.sh 5_12_0"
displayName: 'Select Xamarin Version'
- task: InstallAppleCertificate#2
displayName: 'Install an Apple certificate'
inputs:
certSecureFile: '6f1c094d-c147-41e0-9bc6-c9fe9a40b2e6'
certPwd: '$(P12password)'
- task: InstallAppleProvisioningProfile#1
displayName: 'Install an Apple provisioning profile'
inputs:
provProfileSecureFile: 'a883a983-6027-4382-afd4-94b52736323c'
- task: NuGetToolInstaller#0
displayName: 'Use NuGet'
inputs:
versionSpec: 4.x
- task: NuGetCommand#2
displayName: 'NuGet restore'
inputs:
restoreSolution: '$(Parameters.solution)'
- task: XamariniOS#2
displayName: 'Build Xamarin.iOS '
inputs:
solutionFile: Src/MoneyFox.Ios/MoneyFox.iOS.csproj
configuration: '$(BuildConfiguration)'

Answer 1

You should be able to select the correct version of Mono and Xcode now based on this documentation. In Azure DevOps in both the build and the release pipelines (before the Xamarin.iOS build task and the release task respectively), I added a command line task that runs the following:
echo 'Updating fastlane...'
sudo gem install fastlane
echo 'Selecting Mono version...'
/bin/bash -c "sudo $AGENT_HOMEDIRECTORY/scripts/select-xamarin-sdk.sh 5_16_0"
echo 'Selecting Xcode version...'
/bin/bash -c "echo '##vso[task.setvariable variable=MD_APPLE_SDK_ROOT;]'/Applications/Xcode_10.1.app;sudo xcode-select --switch /Applications/Xcode_10.1.app/Contents/Developer"

Answer 2

In case it helps: the build SDK and the deployment target are different things. I'm building using the 12.1 SDK, but my deployment target, and minimum OS version, are both set to 8.0.

Answer 3

Check 'MinimumOSVersion' key in info.plist.
If it doesn't exist, add it.
<key>MinimumOSVersion</key>
<string>11.0</string>

Answer 4

This looks like a problem with availability of the right version of the Xamarin.iOS library (12.0 or higher) on the DevOps build machine. While it was according to my observations included with recent updates of VS 15.9 (for Windows), or potentially via the Tools for Xamarin extension (still not sure here completely how it gets to a local machine), the VS on the Azure DevOps build machine is 15.8 and comes with default Xamarin.iOS 11.
So the options here are really use your own build machine with or wait for 15.9 to [hopefully] come to the DevOps machines in time.