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    <p>The following code creates three gestures: </p> <ul> <li><p>A tap gesture drops a circle on the view (just so you can see how the <code>CAShapeLayer</code> is created);</p></li> <li><p>A pan gesture moves the circle (assuming you started moving from within the circle); and</p></li> <li><p>A pinch gesture resizes the circle.</p></li> </ul> <p>Thus that might look like:</p> <pre><code>#import &lt;QuartzCore/QuartzCore.h&gt; #import &lt;UIKit/UIGestureRecognizerSubclass.h&gt; @interface ViewController () @property (nonatomic, weak) CAShapeLayer *circleLayer; @property (nonatomic) CGPoint circleCenter; @property (nonatomic) CGFloat circleRadius; @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; // create tap gesture UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)]; [self.view addGestureRecognizer:tap]; // create pan gesture UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)]; [self.view addGestureRecognizer:pan]; // create pinch gesture UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinch:)]; [self.view addGestureRecognizer:pinch]; } // Create a UIBezierPath which is a circle at a certain location of a certain radius. // This also saves the circle's center and radius to class properties for future reference. - (UIBezierPath *)makeCircleAtLocation:(CGPoint)location radius:(CGFloat)radius { self.circleCenter = location; self.circleRadius = radius; UIBezierPath *path = [UIBezierPath bezierPath]; [path addArcWithCenter:self.circleCenter radius:self.circleRadius startAngle:0.0 endAngle:M_PI * 2.0 clockwise:YES]; return path; } // Create a CAShapeLayer for our circle on tap on the screen - (void)handleTap:(UITapGestureRecognizer *)gesture { CGPoint location = [gesture locationInView:gesture.view]; // if there was a previous circle, get rid of it [self.circleLayer removeFromSuperlayer]; // create new CAShapeLayer CAShapeLayer *shapeLayer = [CAShapeLayer layer]; shapeLayer.path = [[self makeCircleAtLocation:location radius:50.0] CGPath]; shapeLayer.strokeColor = [[UIColor redColor] CGColor]; shapeLayer.fillColor = nil; shapeLayer.lineWidth = 3.0; // Add CAShapeLayer to our view [gesture.view.layer addSublayer:shapeLayer]; // Save this shape layer in a class property for future reference, // namely so we can remove it later if we tap elsewhere on the screen. self.circleLayer = shapeLayer; } // Let's move the CAShapeLayer on a pan gesture (assuming we started // pan inside the circle). - (void)handlePan:(UIPanGestureRecognizer *)gesture { static CGPoint oldCenter; if (gesture.state == UIGestureRecognizerStateBegan) { // If we're starting a pan, make sure we're inside the circle. // So, calculate the distance between the circle's center and // the gesture start location and we'll compare that to the // radius of the circle. CGPoint location = [gesture locationInView:gesture.view]; CGPoint translation = [gesture translationInView:gesture.view]; location.x -= translation.x; location.y -= translation.y; CGFloat x = location.x - self.circleCenter.x; CGFloat y = location.y - self.circleCenter.y; CGFloat distance = sqrtf(x*x + y*y); // If we're outside the circle, cancel the gesture. // If we're inside it, keep track of where the circle was. if (distance &gt; self.circleRadius) gesture.state = UIGestureRecognizerStateCancelled; else oldCenter = self.circleCenter; } else if (gesture.state == UIGestureRecognizerStateChanged) { // Let's calculate the new center of the circle by adding the // the translationInView to the old circle center. CGPoint translation = [gesture translationInView:gesture.view]; CGPoint newCenter = CGPointMake(oldCenter.x + translation.x, oldCenter.y + translation.y); // Update the path for our CAShapeLayer self.circleLayer.path = [[self makeCircleAtLocation:newCenter radius:self.circleRadius] CGPath]; } } // Let's resize circle in the CAShapeLayer on a pinch gesture (assuming we have // a circle layer). - (void)handlePinch:(UIPinchGestureRecognizer *)gesture { static CGFloat oldCircleRadius; if (gesture.state == UIGestureRecognizerStateBegan) { if (self.circleLayer) oldCircleRadius = self.circleRadius; else gesture.state = UIGestureRecognizerStateCancelled; } else if (gesture.state == UIGestureRecognizerStateChanged) { CGFloat newCircleRadius = oldCircleRadius * gesture.scale; self.circleLayer.path = [[self makeCircleAtLocation:self.circleCenter radius:newCircleRadius] CGPath]; } } @end </code></pre>
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    1. POBest way to draw circle on top of UIImageView IOS
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    1. COThanks Rob, very clear and just what i was after, i would give two ticks if i could :-)
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      1. USMrBeanzy
    2. CO@Rob the above code is great can you also help me in knowing how to crop the image portion under the circle into a separate image ? Thanks
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      1. USvishal dharankar
    3. CO@Rob also gesture.state = UIGestureRecognizerStateCancelled; gives an error on ios7
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