CAKeyframeAnimation stops for some angle values of CGPathAddArc

Question

i am trying to create an animation, in which a circle rotates around the center of the view.

I want the circle to appear under the location of the tap gesture, therefore i calculate distance and angle between the center of the view and the circle.

I then set these values inside the CGPathAddArc for the animation path.

This seem to work rather well, but once in a while, after having performed a whole rotation, the circle will stop for a short while, before restarting. By playing around, i found out that this must be related to the start and stop angles of the CGPathAddArc function, as setting standard values like -M_PI to M_PI will not cause the issue.

My code is:

CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    pathAnimation.fillMode = kCAFillModeRemoved;
    pathAnimation.removedOnCompletion = YES;
    pathAnimation.duration = 4.0;
    pathAnimation.repeatCount = HUGE_VALF;

    CGMutablePathRef curvedPath = CGPathCreateMutable();



    //get the angle and dinstance of location in relation to center of view (mathematics)
    CGFloat angle = atan2f(location.y -self.view.center.y, location.x - self.view.center.x);
    CGFloat distance = hypotf(location.x - self.view.center.x, location.y - self.view.center.y);
    NSLog(@"angle: %f", angle);
    CGPathAddArc(curvedPath, NULL, self.view.center.x, self.view.center.y, distance, angle, angle + 2 * M_PI, NO);

    //Now we have the path, we tell the animation we want to use this path - then we release the path
    pathAnimation.path = curvedPath;
    CGPathRelease(curvedPath);

    //Add the animation to the circleView - once you add the animation to the layer, the animation starts
    [self.view addSubview:circle];
    [circle.layer addAnimation:pathAnimation forKey:@"moveTheSquare"];

location holds the coordinates of the touch event, the circle object is created before this code snippet. Any help would be greatly appreciated.

Answer 1

Adding this would smooth the animation out evenly:

pathAnimation.calculationMode = kCAAnimationPaced;

Just tested it.

Nice calculation, by the way.

Hope this helps.