Xamarin iOS CustomRenderer button background suddenly not working - xamarin

Question

I have the following CustomRenderer to apply a style to buttons in my iOS project of my cross-platform Xamarin.Forms app.
The button used to have rounded edges, white text, and a blue gradient background.
Everything has been working just fine up until I downloaded Xcode 8.1. Since moving to 8.1, the same code will not present the background gradient. Can anyone see how I could change my code to get the background gradient working again?
The border radius and text color are all working as usual - it's just the background gradient which is missing.
[assembly: ExportRenderer(typeof(CustomButton), typeof(CustomButtonRenderer))]
namespace MyApp.Forms.iOS.CustomRenderers
{
class CustomButtonRenderer : ButtonRenderer
{
public override void LayoutSubviews()
{
foreach (var layer in Control?.Layer.Sublayers.Where(layer => layer is CAGradientLayer))
{
layer.Frame = Control.Bounds;
}
base.LayoutSubviews();
}
protected override void OnElementChanged(ElementChangedEventArgs<Button> e)
{
base.OnElementChanged(e);
if (e.OldElement == null)
{
var gradient = new CAGradientLayer();
gradient.CornerRadius = Control.Layer.CornerRadius = 10;
gradient.Colors = new CGColor[]
{
UIColor.FromRGB(153, 204, 255).CGColor,
UIColor.FromRGB(51, 102, 204).CGColor
};
var layer = Control?.Layer.Sublayers.LastOrDefault();
Control?.Layer.InsertSublayerBelow(gradient, layer);
Control.SetTitleColor(UIColor.White, UIControlState.Normal);
Control.Layer.BorderColor = UIColor.FromRGB(51, 102, 204).CGColor;
Control.Layer.BorderWidth = 1;
}
}
}
}

Answer 1

Ok so I have finally worked out what was going on. In the LayoutSubviews method where I was setting each layer.Frame to the value of Control.Bounds, I noticed that Control.Bounds was a rectangle full of zeros, so my gradient was therefore 0 pixels in size.
I have modified the method as follows and it now works as expected again:
public override void LayoutSubviews()
{
var newBounds = Element.Bounds.ToRectangleF();
foreach (var layer in Control?.Layer.Sublayers.Where(layer => layer is CAGradientLayer))
{
layer.Frame = new CGRect(0, 0, newBounds.Width, newBounds.Height);
}
base.LayoutSubviews();
}
I'm not sure if this is a hack, but it seems to do the job - for now...