Question

I have used this code to animate the circle along a fixed custom route path along two buttons using their x & y coordinates.
Now I want to know the exact location of circle at each route while it is rotating or animating how could I know this?

- (void) animateCicleAlongPath:(NSInteger)pt1:(NSInteger)pt2
{
    UIButton *animatebtn1 = (UIButton *)[self.view viewWithTag:pt1];
    UIButton *animatebtn2 = (UIButton *)[self.view viewWithTag:pt2];
    NSLog(@"%@",animatebtn1);
    NSLog(@"%@",animatebtn2);

    NSLog(@"%@",NSStringFromCGRect(circleView.frame));

    int a1;
    int a2;
    int b1;
    int b2;
    a1=animatebtn1.frame.origin.x;
    a2=animatebtn1.frame.origin.y;
    b1=animatebtn2.frame.origin.x;
    b2=animatebtn2.frame.origin.y;

    pathAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    [UIView setAnimationDidStopSelector:@selector(animationDidStart:)];

    pathAnimation.calculationMode = kCAAnimationPaced;

    pathAnimation.fillMode = kCAFillModeForwards;
    pathAnimation.removedOnCompletion = YES;

    CGMutablePathRef curvedPath = CGPathCreateMutable();

    CGPathMoveToPoint(curvedPath, NULL, b1, b2);

    NSLog(@"%@",[finalpath description]);
    for (int i=0; i<finalpath.count; i++) {
        int j=[[finalpath objectAtIndex:i]intValue];
        UIButton *animatebtn = (UIButton *)[self.view viewWithTag:j];
        int p1=animatebtn.frame.origin.x;
        int p2=animatebtn.frame.origin.y;
        CGPathAddLineToPoint(curvedPath, NULL, p1,p2);
    }


    pathAnimation.path = curvedPath;

    CGPathRelease(curvedPath);

    UIGraphicsBeginImageContext(CGSizeMake(20,20));
    //  CGContextRef ctx = UIGraphicsGetCurrentContext();   
    //Set context variables
    CGContextSetLineWidth(context, 1.5);
    CGContextSetFillColorWithColor(context, [UIColor redColor].CGColor);
    CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
    //Draw a circle - and paint it with a different outline (white) and fill color (green)
    CGContextAddEllipseInRect(context, CGRectMake(1, 1, 18, 18));
    CGContextDrawPath(context, kCGPathFillStroke);

    UIImage *circle = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    circleView = [[UIImageView alloc] initWithImage:circle];
    [imageScrollView addSubview:circleView];

    [imageScrollView bringSubviewToFront:circleView];
    [circleView setHidden:NO];
    circleView.alpha=1;
    pathAnimation.speed=0.5;

    pathAnimation.duration=10;
    circleView.animationDuration=10;
    [circleView.layer addAnimation:pathAnimation forKey:@"moveTheSquare"];

    [circleView release];

}

Answer 1

CALayer provides a method, -presentationLayer, which returns a layer with the current animation state applied. So long as you have the layer being animated, you can inspect the current position of animation through the presentation layer.