如何知道在自定義路徑上旋轉的圓的當前位置？

Question

我已經使用此代碼沿着沿着兩個按鈕的固定自定義路徑路徑使用它們的x座標x &來設置動畫。 現在我想知道每條路線在旋轉或動畫時的圓的確切位置，我怎麼知道這一點？

- (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

的CALayer提供了一種方法，-presentationLayer，它返回與當前動畫狀態的層施加。只要您的圖層具有動畫效果，您就可以通過表示層檢查動畫的當前位置。