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First, you can try to add SKStoreReviewController.RequestReview(Window.WindowScene) in the FinishedLaunching method of your xxx.ios->AppDelegate.cs; start the project to see if it is correct.

If the above method goes wrong, using DependencyService is the right way to go.

Here is the interface code:

• Updated Answer This can be resolved using MSBuild task instead, as the collogues mentioned below. However, in my case this still lead to the same error. After investigating the pipeline. The root cause has been identified: Both in MSBuild@1 and XamariniOS@2 tasks you should target the specific iOS Project and not the solution file, like so:

" - task: MSBuild@1 inputs: solution: 'PathToIosProject/myproject.iOS.csproj' configuration: '$(BuildConfiguration)' msbuildArguments: /t:restore

" - task: XamariniOS@2 inputs: solutionFile: PathToIosProject/myproject.iOS.csproj' configuration: '$(BuildConfiguration)' packageApp: true signingIdentity: $(APPLE_CERTIFICATE_SIGNING_IDENTITY)

• Old Answer

We have managed to resolve the issue. The root cause of it seems to be an update to the mono framework in the MacOS pipeline build agent. In order to fix it, we need a script for downloading and installing an older version of the mono framework as a first step of the build pipeline like so: link to the pipeline tasks photo

This is the code of the bash scrip used in the task:

#!/bin/bash set -ex

MONO_MACOS_PKG_DOWNLOAD_URL='https://download.mono-project.com/archive/6.12.0/macos-10-universal/MonoFramework-MDK-6.12.0.100.macos10.xamarin.universal.pkg'

mkdir -p /tmp/mono-install cd /tmp/mono-install

mono --version

wget -q -O ./mono-installer.pkg "$MONO_MACOS_PKG_DOWNLOAD_URL"

sudo installer -pkg ./mono-installer.pkg -target /

mono --version

ls -alh /Library/Frameworks/Mono.framework/Versions/Current

In this case, there can be race-condition. If two (or more threads) simultaneously reads Instance for first time, there will be created multiple instances of DataSingleton. However every other read will get just one instance. It depends on your scenario, if it is ok.

From the error: [0:] Binding: '160' cannot be converted to type 'Xamarin.Forms.Constraint' You can see that it can't convert the integer to the type Constraint that is expected by the binding expression.

When you do this:

I was able to fix the exception, but now my toolbar is completely gone and I created a new stackoverflow post for that problem: Xamarin Forms Android Toolbar missing after migration to Flyout and AppCompat

The solution for this problem here was to delete the layout.xml file and to use the following values in the styles.xml file:

Thank you for providing the information regarding this issue, we have reported it to the R&D team. at the same time, we have provided a workaround, you can downgrade the Account SDK version to 5.0.3.302, which should solve your problem.

Class reference through a string is now deprecated. You need to change this line:

As you can see, OnStart returns void, not Task, so it's not intended to be asynchronous. You made it async void but caller (framework code which calls OnStart) has no means to wait for that async operation to complete. For caller, OnStart completes right when await Task.Delay hits (that's when OnStart returns), and so it continues to other stuff. When await Task.Delay completes and you set MainPage - you are not actually in OnStart stage of initialization process, that stage has already been completed 100 milliseconds ago.

Consider this example which should clarify it:

Two changes needed:

1. The type of the bound property (SelectedElement) must match the type of the CollectionView property (SelectedItems). XF Doc says the type is IList.

2. Your bound property (if the correct type) will get set to the SelectedItems list when the binding is resolved (page is loaded; BindingContext set). It starts out as an empty list. As selection changes, the list's contents change. But the list object itself is the same object, so the setter never gets called again.

So how do you see a change? Via either SelectionChangedCommand, or SelectionChanged event.

To use SelectionChangedCommand:

add to CollectionView XAML: