Question

this is a simple code form Brad Larson u-tunes course 😉

CABasicAnimation *move = [CABasicAnimation animationWithKeyPath:@"position"];
move.duration = 1.0f;
move.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
move.removedOnCompletion = NO;
move.fillMode = kCAFillModeForwards;

CGPoint currentPosition = l.position;
CGPoint newPosition = CGPointMake(currentPosition.x + 60.0f, currentPosition.y + 60.0f);
move.toValue = [NSValue valueWithCGPoint:newPosition];
[l addAnimation:move forKey:@"position"];
l.position = newPosition;

in the last row i change the position to reflect the final state of layer because animation does not.
But when i execute this code the animation isn’t executed and layer move (in 1/4 of sec) to newposition.

someone can explain me how to animate layer’s position correctly?

a second question…when i run this code…every subsequent access to property “position” will perform the same animation?

thanks.

Answer 1

Ditch the last line, the l.position = newPosition;. Your animation will already take care of that, and by using that property setter, you’re implicitly giving the layer Core Animation’s default .25-second action.

Also, no, subsequent changes in the position of your layer will not use your 1-second animation. The properties you’re using look pretty much identical to the default animation, though, aside from the duration; a quicker way to accomplish what you’re doing would be something like this.

CGPoint currentPosition = l.position;
CGPoint newPosition = CGPointMake(currentPosition.x + 60.0f, currentPosition.y + 60.0f);

[CATransaction begin];
    [CATransaction setAnimationDuration:1.0];
    l.position = newPosition;
[CATransaction commit];