Create An Explicit Animation

PDF for offline use
Sample Code:
Related SDKs:

Let us know how you feel about this

Translation Quality


0/250

This recipe shows how to create an explicit animation using Core Animation.

Recipe

Follow these steps to create the animation:

  • Add an image named sample.png to the project with a Build Action of Content.
  • Add the following Using directives:
using CoreGraphics;
using CoreAnimation;
using Foundation;
  • In a UIViewController subclass, declare a CALayer class variable from the CoreAnimation namespace.
CALayer layer;
  • In ViewDidLoad method, create the layer and set its content to be the image.
layer = new CALayer ();
layer.Bounds = new CGRect (0, 0, 50, 50);
layer.Position = new CGPoint (150, 150);
layer.Contents = UIImage.FromFile ("sample.png").CGImage;
layer.ContentsGravity = CALayer.GravityResizeAspectFill;
  • Add the layer as a sub layer of the view’s layer.
View.Layer.AddSublayer (layer);
  • In the ViewDidAppear method, create a CABasicAnimation to animate the position of the layer.
public override void ViewDidAppear (bool animated)
{
    base.ViewDidAppear (animated);

    var pt = layer.Position;
    layer.Position = new CGPoint (150, 350);

    var basicAnimation = CABasicAnimation.FromKeyPath ("position");
    basicAnimation.TimingFunction = CAMediaTimingFunction.FromName (CAMediaTimingFunction.EaseInEaseOut);
    basicAnimation.From = NSValue.FromCGPoint (pt);
    basicAnimation.To = NSValue.FromCGPoint (new CGPoint (150, 350));
    basicAnimation.Duration = 2;

    layer.AddAnimation (basicAnimation, "position");

}

Additional Information

The code creates a layer and adds an image to it. Before creating the animation the final interpolated value of the layer’s position is set so that the image will remain at the final position at the end of the animation. A timing function is used to determine how the position is animated over time. When the animation is added to the layer, the animation will happen on the next pass through the run loop, animating the property set in the key path, which in this case is the position.

Xamarin Workbook

If it's not already installed, install the Xamarin Workbooks app first. The workbook file should download automatically, but if it doesn't, just click to start the workbook download manually.