How to move a ball horizontally with CABasicAnimation and stop the ball at the correct place

I'm trying to write a game and I'm a bit stuck with this animation. I have a ball that is animating horizontally in my screen. Here is the code:

CABasicAnimation *horizontalBallAnimation = [CABasicAnimation animationWithKeyPath:@"position"];
[horizontalBallAnimation setFromValue:[NSValue valueWithCGPoint:CGPointMake(50.0, 300.0 )]];
[horizontalBallAnimation setToValue:[NSValue valueWithCGPoint:CGPointMake(220.0, 300.0 )]];

horizontalBallAnimation.delegate = self;
horizontalBallAnimation.repeatCount = 1e100f;
//horizontalBallAnimation.autoreverses = YES;
horizontalBallAnimation.duration = 2.0;

[gameBallLayer addAnimation:horizontalBallAnimation forKey:@"horizontalBallAnimation"];

This is works great. However my problem is that when I stop the animation - just by tapping on the screen - the ball before going to the right positi开发者_如何学Goon;

[gameLogic ballGameObject].x = [[[gameBallLayer presentationLayer] valueForKeyPath:@"position.x"] doubleValue];
    [gameLogic ballGameObject].y = [[[gameBallLayer presentationLayer] valueForKeyPath:@"position.y"] doubleValue];

first animates to the "ToValue" of the horizontalBallAnimation. Then, it goes to the correct value set by the gameObject. Someone can please help me with this?

---

What you need to do is set the target position within aCATransactionthat disables actions. For example:

//--------------------------------------------------------------------------------------------------

#pragma mark - CAAnimation Delegate Methods 

//--------------------------------------------------------------------------------------------------

- (void)animationDidStart:(CAAnimation *)theAnimation
{
    [CATransaction begin];
    [CATransaction setValue:(id)kCFBooleanTrue
                     forKey:kCATransactionDisableActions];

    // Set the layer's target position here.        

    [CATransaction commit];
}