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POanimating the length of circular arrow mask in Core Animation
 

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  1. POanimating the length of circular arrow mask in Core Animation
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    <p>I've created a circular animation using CAShapeLayer and masking. Here is my code:</p> <pre><code>- (void) maskAnimation{ animationCompletionBlock theBlock; imageView.hidden = FALSE;//Show the image view CAShapeLayer *maskLayer = [CAShapeLayer layer]; CGFloat maskHeight = imageView.layer.bounds.size.height; CGFloat maskWidth = imageView.layer.bounds.size.width; CGPoint centerPoint; centerPoint = CGPointMake( maskWidth/2, maskHeight/2); //Make the radius of our arc large enough to reach into the corners of the image view. CGFloat radius = sqrtf(maskWidth * maskWidth + maskHeight * maskHeight)/2; //Don't fill the path, but stroke it in black. maskLayer.fillColor = [[UIColor clearColor] CGColor]; maskLayer.strokeColor = [[UIColor blackColor] CGColor]; maskLayer.lineWidth = 60; CGMutablePathRef arcPath = CGPathCreateMutable(); //Move to the starting point of the arc so there is no initial line connecting to the arc CGPathMoveToPoint(arcPath, nil, centerPoint.x, centerPoint.y-radius/2); //Create an arc at 1/2 our circle radius, with a line thickess of the full circle radius CGPathAddArc(arcPath, nil, centerPoint.x, centerPoint.y, radius/2, 3*M_PI/2, -M_PI/2, NO); maskLayer.path = arcPath;//[aPath CGPath];//arcPath; //Start with an empty mask path (draw 0% of the arc) maskLayer.strokeEnd = 0.0; CFRelease(arcPath); //Install the mask layer into out image view's layer. imageView.layer.mask = maskLayer; //Set our mask layer's frame to the parent layer's bounds. imageView.layer.mask.frame = imageView.layer.bounds; //Create an animation that increases the stroke length to 1, then reverses it back to zero. CABasicAnimation *swipe = [CABasicAnimation animationWithKeyPath:@"strokeEnd"]; swipe.duration = 5; swipe.delegate = self; [swipe setValue: theBlock forKey: kAnimationCompletionBlock]; swipe.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]; swipe.fillMode = kCAFillModeForwards; swipe.removedOnCompletion = NO; swipe.autoreverses = YES; swipe.toValue = [NSNumber numberWithFloat: 1.0]; [maskLayer addAnimation: swipe forKey: @"strokeEnd"]; } </code></pre> <p>This is my background image: <img src="https://i.stack.imgur.com/j7dtW.png" alt="enter image description here"></p> <p>This what is looks like when I run the animation: <img src="https://i.stack.imgur.com/8oF72.png" alt="enter image description here"></p> <p>But what I want, the arrow head is missing how to add this? <img src="https://i.stack.imgur.com/v0Zqy.png" alt="enter image description here"></p>
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    1. COYou may be able to create a mask layer with two sublayers (one is the strokeEnd animated shape layer for your code and one would be a triangle animating its position along the same circular path). I haven't tried it though.
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      1. USDavid Rönnqvist
 

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