How to get the animated object's position in the middle of the animation

[seagulljl]

I'm a new developer. My question is: is there a direct way to get the x,y position of an animated view in the middle of the animation?
I have this code (from the Stanford iPhone course in youtube) that moves the stalker UIView to the position of the touch:

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    [UIView beginAnimations:@"stalk" context:nil];
    UITouch *touch = [touches anyObject];
    [UIView setAnimationDuration:10];
    [UIView setAnimationBeginsFromCurrentState:YES];
    stalker.center = [touch locationInView:self];
    [UIView commitAnimations];
}

I want to modify the code such that stalker will not move to the touch location but to a different location I want to calculate, which is relative on the stalker view position at the time of the touch.
It should be possible to do by calculating the time passed from the beginning of the animation till the touch, but I want to ask if there's a more direct way. I assume that the current x,y are stored somewhere under the hood - the question is how to access them.
Thanks!

[rocotilos]

There is no way that I know of that can do what you want. block animations like this are applied IMMEDIATELY when u set .center = location, only the iOS plays it out according to your animation settings.

I'd suggest you to use NSTimers and gradually moving the object by a speed variable. Then you can evaluate the object location at anytime as you please.

[fiftysixty]

Originally Posted by rocotilos

There is no way that I know of that can do what you want. block animations like this are applied IMMEDIATELY when u set .center = location, only the iOS plays it out according to your animation settings.

I'd suggest you to use NSTimers and gradually moving the object by a speed variable. Then you can evaluate the object location at anytime as you please.

Actually, Core Animation has three "layers": model, presentation and render. Model is where the changes are applied instantly, and that is what you get when you ask for the layer of an UIView. However, you can get the presentation layer of a CALayer just by calling [layer presentationLayer], and the presentation layer will have all values set according to the animation(s) in progress, so you can query them there.

[rocotilos]

Originally Posted by fiftysixty

Actually, Core Animation has three "layers": model, presentation and render. Model is where the changes are applied instantly, and that is what you get when you ask for the layer of an UIView. However, you can get the presentation layer of a CALayer just by calling [layer presentationLayer], and the presentation layer will have all values set according to the animation(s) in progress, so you can query them there.

Hm. I didn't know that. Thanks for telling me. You're awesome!