[Bug] [iOS] Button, ImageButton and RadioButton have a minimum height of 44px

[velocitysystems]

Description

Button, ImageButton and RadioButton have a minimum height of 44px on iOS.
This value is hard-coded into the renderer and forces a minimum height.

Note: No minimum height is forced on other platforms including Android or UWP.

Steps to Reproduce

1. Create an ImageButton
2. Use an image with a height less than 44px or set a HeightRequest.

Expected Behavior

The button should renderer the same across all platforms.

Actual Behavior

The button image is not rendered properly. Why? See code excerpt below:

Xamarin.Forms/Xamarin.Forms.Platform.iOS/Renderers/ImageButtonRenderer.cs

Lines 13 to 43 in db45ed2

	public class ImageButtonRenderer : ViewRenderer<ImageButton, UIButton>, IImageVisualElementRenderer
	{
	bool _isDisposed;
	// This looks like it should be a const under iOS Classic,
	// but that doesn't work under iOS
	// ReSharper disable once BuiltInTypeReferenceStyle
	// Under iOS Classic Resharper wants to suggest this use the built-in type ref
	// but under iOS that suggestion won't work
	readonly nfloat _minimumButtonHeight = 44; // Apple docs
	[Preserve(Conditional = true)]
	public ImageButtonRenderer() : base()
	{
	ButtonElementManager.Init(this);
	BorderElementManager.Init(this);
	ImageElementManager.Init(this);
	}
	public override SizeF SizeThatFits(SizeF size)
	{
	var result = base.SizeThatFits(size);
	if (result.Height < _minimumButtonHeight)
	{
	result.Height = _minimumButtonHeight;
	}
	return result;
	}

Basic Information

• Version with issue: All XF versions
• Last known good version: N/A

Workaround

Create a custom ImageButtonRenderer and override the SizeThatFits method:

/// <inheritdoc/>
public override CGSize SizeThatFits(CGSize size)
{
    return Control.SizeThatFits(size);
}

If approved, I am happy to create a PR to fix this issue.