Getting ready

We will work on the existing CustomViewApp project we created in the preceding recipe. Open the project in Xamarin Studio.

How to do it…

Perform the following steps to complete this recipe:

How it works…

The UIAppearance class is basically a proxy to the specific properties of each control. In Xamarin.iOS, we can access each control's proxy through its static Appearance property. The changes we make to this object's properties will reflect on the instances of the object throughout the app. In this case, we set the BackgroundColor attribute of all UILabel instances to blue using the following code:

UILabel.Appearance.BackgroundColor = UIColor.Blue;

However, we can provide different behavior for specific instances of UILabel. For example, we want the labels that are contained in MyView objects to have a green background. We accomplish this by calling the static AppearanceWhenContainedIn method, as shown in the following code:

var labelStyle = UILabel.AppearanceWhenContainedIn(typeof(MyView));

We pass the types of objects for which we want to set the specific style. In this case, passing typeof(MyView) instructs the appearance proxy to make sure that we are referring to objects that are only contained in MyView objects. We then set the value we want to the object that was returned from this method, as shown in the following code:

labelStyle.BackgroundColor = UIColor.Green;

There's more…

Through the AppearanceWhenContainedIn method, we can target a more specific set of styling. For example, consider the following line of code:

var labelStyle = UILabel.AppearanceWhenContainedIn(typeof(AnotherView), typeof(MyView));

This would return a styling object that acts as a proxy for all instances of UILabel, which are part of MyView, only when MyView is included in AnotherView objects.

MyView.GetAppearance<MyView>().BackgroundColor = UIColor.Yellow;
// We can also call GetAppearance on the base class:
//UIView.GetAppearance<MyView>().BackgroundColor = UIColor.Yellow;

See also