[Bug] Can't use DynamicBinding in OnPlatform

Tommigun1980 commented 3 years ago

Description

Using a DynamicBinding in an OnPlatform clause results in a 'Cast is not valid' error. This is problematic because it breaks dynamic theming.

Steps to Reproduce

<NavigationPage
    ...
    >
    <NavigationPage.BarTextColor>
            <OnPlatform x:TypeArguments="Color">
                <On Platform="iOS" Value="{DynamicResource SomeColor}" />
                <On Platform="Android" Value="White" />
            </OnPlatform>
        </NavigationPage.BarTextColor >
</NavigationPage>

Expected Behavior

It should not crash with a 'Cast is not valid' error.

Actual Behavior

It crashes with a 'Cast is not valid' error.

Basic Information

Version with issue: Xamarin.Forms 5.0.0-pre4
Last known good version: None

Environment

Show/Hide Visual Studio info

``` === Visual Studio Community 2019 for Mac (Preview) === Version 8.9 Preview (8.9 build 1451) Installation UUID: 22103902-8a07-4928-b566-c12f86da3599 GTK+ 2.24.23 (Raleigh theme) Xamarin.Mac 6.18.0.23 (d16-6 / 088c73638) Package version: 612000113 === Mono Framework MDK === Runtime: Mono 6.12.0.113 (2020-02/4fdfb5b1fd5) (64-bit) Package version: 612000113 === Xamarin Designer === Version: 16.9.0.266 Hash: c4842c761 Branch: remotes/origin/c4842c761b9b6a95407f72278ca7fb42f8f7fdf0 Build date: 2021-01-07 06:17:08 UTC === Roslyn (Language Service) === 3.9.0-3.20619.14+df59a33fd9beff9790e01a2a1ab21e4a1e6921b3 === NuGet === Version: 5.8.0.6860 === .NET Core SDK === SDK: /usr/local/share/dotnet/sdk/5.0.102/Sdks SDK Versions: 5.0.102 5.0.101 5.0.100 3.1.405 3.1.404 3.1.403 MSBuild SDKs: /Applications/Visual Studio.app/Contents/Resources/lib/monodevelop/bin/MSBuild/Current/bin/Sdks === .NET Core Runtime === Runtime: /usr/local/share/dotnet/dotnet Runtime Versions: 5.0.2 5.0.1 5.0.0 3.1.11 3.1.10 3.1.9 === .NET Core 3.1 SDK === SDK: 3.1.405 === Xamarin.Profiler === Version: 1.6.15.68 Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler === Updater === Version: 11 === Apple Developer Tools === Xcode 12.2 (17535) Build 12B45b === Xamarin.Mac === Xamarin.Mac not installed. Can't find /Library/Frameworks/Xamarin.Mac.framework/Versions/Current/Version. === Xamarin.iOS === Version: 14.9.0.27 (Visual Studio Community) Hash: f4c9327fa Branch: main Build date: 2020-11-19 10:57:31-0500 === Xamarin.Android === Version: 11.2.0.0 (Visual Studio Community) Commit: xamarin-android/d16-9/f908d16 Android SDK: /Users/tommikiviniemi/Library/Developer/Xamarin/android-sdk-macosx Supported Android versions: None installed SDK Tools Version: 26.1.1 SDK Platform Tools Version: 30.0.4 SDK Build Tools Version: 30.0.2 Build Information: Mono: 5e9cb6d Java.Interop: xamarin/java.interop/d16-9@1d382be ProGuard: Guardsquare/proguard/v7.0.1@912d149 SQLite: xamarin/sqlite/3.32.2@cfe06e0 Xamarin.Android Tools: xamarin/xamarin-android-tools/main@ad80a42 === Microsoft OpenJDK for Mobile === Java SDK: /Users/tommikiviniemi/Library/Developer/Xamarin/jdk/microsoft_dist_openjdk_1.8.0.25 1.8.0-25 Android Designer EPL code available here: https://github.com/xamarin/AndroidDesigner.EPL === Android SDK Manager === Version: 16.9.0.21 Hash: 57e40ba Branch: remotes/origin/main Build date: 2021-01-08 01:57:14 UTC === Android Device Manager === Version: 16.9.0.14 Hash: 0fdccda Branch: remotes/origin/main Build date: 2021-01-08 01:57:36 UTC === Build Information === Release ID: 809001451 Git revision: cfd15313a6388ef8dada0182e22a058131c46f9d Build date: 2021-01-15 08:42:21-05 Build branch: release-8.9 Xamarin extensions: cfd15313a6388ef8dada0182e22a058131c46f9d === Operating System === Mac OS X 10.16.0 Darwin 20.2.0 Darwin Kernel Version 20.2.0 Wed Dec 2 20:39:59 PST 2020 root:xnu-7195.60.75~1/RELEASE_X86_64 x86_64 ```

Workaround

Use 'StaticResource' instead.

PureWeen commented 3 years ago

Archive.zip

This looks like it's an iOS 14 specific issue. I don't get the exception when running on iOS 13

Tommigun1980 commented 3 years ago

Archive.zip

This looks like it's an iOS 14 specific issue. I don't get the exception when running on iOS 13

Sorry for forgetting to mention iOS version, and thanks for looking into this!

xamarin / Xamarin.Forms