Mastering Core Animation Felix Chern (dryman) 12年9月10日星期⼀一 

Felix Chern (dryman) Research assistant & iOS developer github id: idryman twitter id: @idryman blog: idryman.org 12年9月10日星期⼀一 

Core Animation • Low level objective c rendering and animation classes used by UIView and UIKit • High performance rendering with simple programming model • Lightweight data structure 12年9月10日星期⼀一 

- classes • CAAnimation • CAAnimationGroup • CABasicAnimation • CADisplayLink • CAEAGLLayer • CAKeyframeAnimation • CALayer • CAEmitterCell • CAEmitterLayer • CAGradientLayer • CAMediaTimingFunction • CAPropertyAnimation • CAScrollLayer • CATextLayer • CATiledLayer • CATransaction • CATransition - protocols • CAAction • CALayoutManager • CAMediaTiming QuartzCore/QuartzCore.h 12年9月10日星期⼀一 

- classes • CAAnimation • CAAnimationGroup • CABasicAnimation • CADisplayLink • CAEAGLLayer • CAKeyframeAnimation • CALayer • CAEmitterCell • CAEmitterLayer • CAGradientLayer • CAMediaTimingFunction • CAPropertyAnimation • CAScrollLayer • CATextLayer • CATiledLayer • CATransaction • CATransition - protocols • CAAction • CALayoutManager • CAMediaTiming Layer provides contents 12年9月10日星期⼀一 

- classes • CAAnimation • CAAnimationGroup • CABasicAnimation • CADisplayLink • CAEAGLLayer • CAKeyframeAnimation • CALayer • CAEmitterCell • CAEmitterLayer • CAGradientLayer • CAMediaTimingFunction • CAPropertyAnimation • CAScrollLayer • CATextLayer • CATiledLayer • CATransaction • CATransition - protocols • CAAction • CALayoutManager • CAMediaTiming Animation defines how properties are animated 12年9月10日星期⼀一 

- classes • CAAnimation • CAAnimationGroup • CABasicAnimation • CADisplayLink • CAEAGLLayer • CAKeyframeAnimation • CALayer • CAEmitterCell • CAEmitterLayer • CAGradientLayer • CAMediaTimingFunction • CAPropertyAnimation • CAScrollLayer • CATextLayer • CATiledLayer • CATransaction • CATransition - protocols • CAAction • CALayoutManager • CAMediaTiming These allows you to create custom animations and Core Animation add-ons 12年9月10日星期⼀一 

• Much like UIView • can set content image, or draw with Quartz 2D • When you change properties, you will trigger implicit animations CALayer Emitter Layer and Cells CALayer with border and corner radius 12年9月10日星期⼀一 

CAAnimation • implicit • layer.position = CGPointMake(x,y); • explicit • setup CAAnimation • layer addAnimation: forKey: • layer removeAnimationForKey: 12年9月10日星期⼀一 

Explicit CAAnimation CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"opacity"]; animation.fromValue = @1.0; animation.toValue = @0.0; animation.autoreverse = YES; animation.repeatCount = INFINITY; animation.duration = 2.0; [layer addAnimation: animation forKey:@"animateOpacity"]; 12年9月10日星期⼀一 

time property CABasicAnimation fromValue: toValue: 12年9月10日星期⼀一 

time property CABasicAnimation fromValue: toValue: 12年9月10日星期⼀一 

time property CABasicAnimation fromValue: toValue: time property CAKeyFrameAnimation fromValue: toValue: 12年9月10日星期⼀一 

time property CABasicAnimation fromValue: toValue: time property CAKeyFrameAnimation fromValue: toValue: NSString * const kCAAnimationLinear; NSString * const kCAAnimationDiscrete; NSString * const kCAAnimationPaced; NSString * const kCAAnimationCubic; NSString * const kCAAnimationCubicPaced; 12年9月10日星期⼀一 

CALayer Properties 1 frame property 2 bounds property 3 position property 4 zPosition property 5 anchorPointZ property 6 anchorPoint property 7 contentsScale property 8 – affineTransform 9 – setAffineTransform: 10 transform property 11 sublayerTransform property 1 contentsGravity property 2 opacity property 3 hidden property 4 masksToBounds property 5 doubleSided property 6 mask property 7 cornerRadius property 8 borderWidth property 9 borderColor property 10 backgroundColor property 11 backgroundFilters property 12 shadowOpacity property 13 shadowRadius property 14 shadowOffset property 15 shadowColor property 16 shadowPath property 17 filters property 18 compositingFilter property 19 style property Most Animations can be created by CAAnimation and CALayer Properties! 12年9月10日星期⼀一 

Excepts... 12年9月10日星期⼀一 

• Scrolling • Animation related to motion • Animation related to AVFoundation inputs • Animation related to other continuous event sources In these cases, we need to control frames ourselves 12年9月10日星期⼀一 

• Pros: • Won’t miss any data sources • Easier to implement with delegates • Cons: • Does not allow frame drop • Harder to control timing Push based 12年9月10日星期⼀一 

Pull based • Pros • Let CADisplayLink setup runloop, timing, and everything else • Cons • Event source has to be pullable 12年9月10日星期⼀一 

-(void)update { float x_acc, y_acc, phi, a_eff; if (self.sharedManager.accelerometerActive) { CMAccelerometerData *accData = self.sharedManager.accelerometerData; x_acc = accData.acceleration.x; y_acc = accData.acceleration.y; } else { x_acc = 0; y_acc = -1.0; } /* calculations */ [CATransaction begin]; [CATransaction setDisableActions:YES]; self.bar1.angle = self.current[0]; self.bar2.angle = self.current[1]; self.bar2.position = self.bar1.tailPosition; self.emitterLayer.emitterPosition = self.bar1.tailPosition; self.emitterCell.birthRate = floorf(fabsf(self.current[2]-self.current[3])*10); self.emitterCell.velocity = fabsf(self.bar1.length*self.current[2]); [CATransaction commit]; } _displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(update)]; [self.displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode]; Pull data from accelerometer Disable implicit animation Setup CADisplayLink for updating data Use [_displayLink setPause:YES] to stop animation 12年9月10日星期⼀一 

Custom CAAnimation • Use CADisplayLink for runloop • CATransaction for stoping implicit animation • Confirms to CAMediaTiming protocol • Use CACurrentMediaTime to pull timestamp 12年9月10日星期⼀一 

Tips and Tricks 12年9月10日星期⼀一 

KeyValue Coding [mySubLayer setName: @"rocket"]; otherLayer.emitterCells = @[mySubLayer, ...]; [otherLayer setValue: @3.0 forKeyPath: @"emitterCells.rocket.emissionRange"]; 12年9月10日星期⼀一 

More on explicit Animation [CATranscation begin]; [CATranscation setDisableActions:YES]; circleLayer.opacity = 0; CABasicAnimation *fade; fade = [CABasicAnimation animationWithKeyPath:@"opacity"]; fade.duration = 1; fade.fromValue = @1.0; fade.toValue = @0.0; fade.beginTime = CACurrentMediaTime() + 3.0; [circleLayer addAnimation:fade forKey:@"fade"]; [CATranscation commit]; The layer opacity will be 0 after the animation ends 12年9月10日星期⼀一 

CAEmitterLayer & CAEmitterCell Off screen rendering 12年9月10日星期⼀一 

Instruments 12年9月10日星期⼀一 

Instruments 12年9月10日星期⼀一 

Instruments 12年9月10日星期⼀一 

Instruments 12年9月10日星期⼀一 

Instruments 12年9月10日星期⼀一 

References • WWDC 2011 section 421: Core Animation Essentials • WWDC 2012 section 211: Building Concurrent User Interface on iOS • WWDC 2012 section 235: iOS App Performance: Responsiveness • WWDC 2012 section 238: iOS App Performance: Graphics and Animations • WWDC 2012 section 506: Optimizing 2D Graphics and Animation Performances • iOS 5 programming -- Pushing the limits ISBN: 1119961327 12年9月10日星期⼀一 

Questions? 12年9月10日星期⼀一