Question

How can I drag an image or button, then when the image is on a specific spot, i.e. (x = 240 y = 240) it will stay there?

Answer 1

I’ll assume iOS as I’m more familiar with it than with OS X.

To make a view draggable, detect a touch dragging it using the following three methods:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;

The trick is that you should store the touch’s location in the view’s superview, then in the 2nd method, update the position of the view itself accordingly. When you detect that the view’s center or origin reached a certain point (don’t check it using ==, it doesn’t work well for floating-point numbers, use some small epsilon to detect whether the view is inside a desired area), you can set a boolean flag on the view, then check that boolean flag in the touchesMoved method and not update the view’s location anymore.