[Bug][iOS] Applying an Effect to Frame adds a shadow

[MarcAlx]

Description

When applying an Effect to a <Frame> a shadow is applied on iOS.

Steps to Reproduce

1. Add an effect to a Frame

<Frame.Effects>
     <controls:ElevationEffect/>
</Frame.Effects>

2. Launch on iOS
3. See the shadow applied (not expected)

Expected Behavior

The effect is applied and no extra shadow is added

Actual Behavior

The effect is applied and a shadow is added like if HasShadow = True

Basic Information

• Version with issue:
• Last known good version: (Forms) 4.4.0.991640
• IDE: Visual Studio Mac 8.4.5 (19)
• Platform Target Frameworks: 4.5.0.142-pre1 +
  • iOS: 4.5.0.142-pre1
  • Android: Doesn't not apply
  • UWP: Not tested
• Android Support Library Version:
• Nuget Packages:
• Affected Devices: iPhone 7 (iOS 13) (real device) also apply on simulator

Screenshots

Ok (4.4.0.991640)

My custom effect is applied (a light shadow)

Ko : (4.5.0.142-pre1 +)

My custom effect is applied and a shadow is added

Reproduction Link

Workaround

Apply your effect as expected then force HasShadow value per platform

<Frame.HasShadow>
      <OnPlatform x:TypeArguments="x:Boolean">
             <On Platform="Android" Value="True" />
             <On Platform="iOS" Value="False" />
      </OnPlatform>
</Frame.HasShadow>

[MarcAlx]

After some toughts, the problem is that there's a different behavior between iOS and Android, which wasn't the case in 4.4

To me the question is: should adding an effect to a Frame should override the shadow ?

PS Setting HasShadow to False on Android cause my effect (which creates a shadow) to not display.

[samhouts]

related to #9519

[lapoPaolacci]

Same bug if you use a custom renderer instead Effect

if (Element.HasShadow)
{
        Layer.MasksToBounds = false;
        Layer.ShadowColor = UIColor.Black.CGColor;
        Layer.ShadowOffset = new CGSize(0, 5);
        Layer.ShadowRadius = 5;
        Layer.ShadowOpacity = 0.24f;
}

[lypefm]

I have the same problem, I use a customrenderer giving a setup and it doesn't work, but in another project with the previous xamarin forms it works

[liveinvarun]

@samhouts Any update on this bug