drawRect circle and animate size/color drawRect circle and animate size/color ios ios

drawRect circle and animate size/color

This is much simpler if you don't draw the circle in drawRect:. Instead, set up your view to use a CAShapeLayer, like this:

@implementation PulseView+ (Class)layerClass {    return [CAShapeLayer class];}

The system sends layoutSubviews to your view whenever it changes size (including when it first appears). We override layoutSubviews to set up the shape and animate it:

- (void)layoutSubviews {    [self setLayerProperties];    [self attachAnimations];}

Here's how we set the layer's path (which determines its shape) and the fill color for the shape:

- (void)setLayerProperties {    CAShapeLayer *layer = (CAShapeLayer *)self.layer;    layer.path = [UIBezierPath bezierPathWithOvalInRect:self.bounds].CGPath;    layer.fillColor = [UIColor colorWithHue:0 saturation:1 brightness:.8 alpha:1].CGColor;}

We need to attach two animations to the layer - one for the path and one for the fill color:

- (void)attachAnimations {    [self attachPathAnimation];    [self attachColorAnimation];}

Here's how we animate the layer's path:

- (void)attachPathAnimation {    CABasicAnimation *animation = [self animationWithKeyPath:@"path"];    animation.toValue = (__bridge id)[UIBezierPath bezierPathWithOvalInRect:CGRectInset(self.bounds, 4, 4)].CGPath;    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];    [self.layer addAnimation:animation forKey:animation.keyPath];}

Here's how we animate the layer's fill color:

- (void)attachColorAnimation {    CABasicAnimation *animation = [self animationWithKeyPath:@"fillColor"];    animation.fromValue = (__bridge id)[UIColor colorWithHue:0 saturation:.9 brightness:.9 alpha:1].CGColor;    [self.layer addAnimation:animation forKey:animation.keyPath];}

Both of the attach*Animation methods use a helper method that creates a basic animation and sets it up to repeat indefinitely with autoreverse and a one second duration:

- (CABasicAnimation *)animationWithKeyPath:(NSString *)keyPath {    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:keyPath];    animation.autoreverses = YES;    animation.repeatCount = HUGE_VALF;    animation.duration = 1;    return animation;}