iOS, Xamarin, UIView, Draw, dynamic animation doesn't works - ios

Question

I'm using MonoDevelop and xamarin for creating iOS application.
I have a view which looks like this:
public class MyView: UIView
{
private Timer _t = new Timer(1000);
private int _i = 0;
public MyView()
{
_t.Elapsed += (sender, e) => {
_i = (_i + 1) % 100;
this.Draw(new Rectangle(0, 0, 110, 110));
};
_t.Enabled = true;
}
public override void Draw(RectangleF rect)
{
base.Draw(rect);
var uiImage = UIImage.FromFile("myImage");
var uiImageView = new UIIMageView(new Rectangle(_i, 0, 10, 10));
uiImageView.Image = uiImage;
AddSubView(uiIMageView);
}
}
I expect that my image will move. But as a result I've only initial static image. Can anybody suggest approach how to do animation like described?

Answer 1

I would suggest modifying your code like so:
public MyView()
{
var uiImage = UIImage.FromFile("myImage");
var uiImageView = new UIIMageView(new Rectangle(0, 0, 10, 10));
uiImageView.Image = uiImage;
AddSubView(uiIMageView);
_t.Elapsed += (sender, e) => {
_i = (_i + 1) % 100;
this.Draw(new Rectangle(_i, 0, 110, 110));
};
_t.Enabled = true;
}
public override void Draw(RectangleF rect)
{
base.Draw(rect);
InvokeOnMainThread(()=>{
uiImageView.Frame = rect;
});
}
I think part of your issue was that the timer Elapsed handler runs on a separate thread than the main UI Thread. Also you it'll be more efficient to not recreate the UIImageView each time.