Question

I have a simple iPhone app with a simple view and a custom view as a child. The child is just a square painted on the main view.

I need to track a touch event that enters this child view but from a touch that started outside the view.

What I’ve tried so far is to add the TouchesBegin/TouchesMoved events to the parent view. Also tried to add the to the child controls directly but that doesn’t track any touches that are not initiated within that control.

The questions are:

a) can I get the control from Position somehow?

b) is this the best way doing this, or is there another way?

Again, I include this video of GamePlay for the game I’m trying to port (on my spare time). It’s not a promotion attempt but illustrates what I’m trying to accomplish. I wrote the Win8 and WP7 version of the game so I’m not trying to copy another persons work here. 🙂 Don’t watch it if you don’t want to know what game it is. The question is still valid without watching this.

http://www.youtube.com/watch?v=13IczvA7Ipo

Thanks

// Johan

Answer 1

I stumbled on the answer myself. In the parent I override TouchesMoved (and Begin and Ended not shown here).

I then iterate the subviews and chech if it’s the view I’m looking for by type and then check if the Frame contains the point. The code below is just concept of course.

    public override void TouchesMoved (NSSet touches, UIEvent evt)
    {
        base.TouchesMoved (touches, evt);

        UITouch touch = touches.AnyObject as UITouch;

        if (touch != null) {
            var rp = touch.LocationInView (touch.View);

            foreach(var sv in this.View.Subviews)
            {
                if(!(sv is LetterControl))
                    continue;

                if(sv.Frame.Contains (rp))
                {
                    Console.WriteLine("LetterControl found");
                }
            }
        }
    }