From the document:
iOS lets you apply visual property settings at a static class level
rather than on individual objects so that the change applies to all
instances of that control in the application.
This functionality is exposed in Xamarin.iOS via a static Appearance
property on all UIKit controls that support it.
So you can set the default appearance values in the first screen:
// Set the default appearance values
UIButton.Appearance.TintColor = UIColor.LightGray;
UIButton.Appearance.SetTitleColor(UIColor.FromRGB(0,127,14), UIControlState.Normal);
UISlider.Appearance.ThumbTintColor = UIColor.Red;
UISlider.Appearance.MinimumTrackTintColor = UIColor.Orange;
UISlider.Appearance.MaximumTrackTintColor = UIColor.Yellow;
UIProgressView.Appearance.ProgressTintColor = UIColor.Yellow;
UIProgressView.Appearance.TrackTintColor = UIColor.Orange;
You can also customize the color by :
UIButton button = new UIButton();
button.SetTitleColor(UIColor.Red, UIControlState.Normal);