15.1 动画介绍
15.2 Core Animation基础
15.3 隐式动画
15.4 显式动画
15.5 关键帧显式动画
15.6 UIView级别动画
15.1 动画介绍
在iOS中动画实现技术主要是：Core Animation。 Core Animation负责所有的滚动、旋转、缩小和放大以及所有的iOS动画效果。其中UIKit类通常都有animated：参数部分，它可以允许是否使用动画。
Core Animation还与Quartz紧密结合在一起，每个UIView都关联到一个CALayer对象，CALayer是Core Animation中的图层。
15.2 Core Animation基础
Core Animation创建动画时候会修改CALayer属性，然后让这些属性流畅地变化。Core Animation相关知识点：
图层，图层是动画发生的地方，CALayer总是与UIView关联，通过layer属性访问。
隐式动画，这是一种最简单的动画，不用设置定时器，不用考虑线程或者重画。
显式动画，是一种使用CABasicAnimation创建的动画，通过CABasicAnimation，可以更明确地定义属性如何改变动 画。
关键帧动画，这是一种更复杂的显式动画类型，这里可以定义动画的起点和终点，还可以定义某些帧之间的动画。
15.3 隐式动画
实例ianimate：
#import#import @interface ianimateViewController : UIViewController { IBOutlet UIImageView *plane;}-(IBAction)movePlane:(id)sender;@end//--m-(IBAction)movePlane:(id)sender { [UIView beginAnimations:nil context:NULL]; CGAffineTransform moveTransform = CGAffineTransformMakeTranslation(180, 200); plane.layer.affineTransform=moveTransform; plane.layer.opacity = 1; [UIView commitAnimations];}
飞机图片的不透明度（opacity）初始为0.25，然后在动画过程中不透明度设置为1.0。这个过程是设置飞机图片对象的层属性的，plane.layer.opacity = 1;
[plane.layer setAffineTransform:moveTransform];设置飞机图片层对象的仿射移动变换。
15.4 显式动画
eanimate关键代码：
#import#import @interface eanimateViewController : UIViewController { IBOutlet UIImageView *plane;}-(IBAction)movePlane:(id)sender;@end//--m-(IBAction)movePlane:(id)sender { CABasicAnimation *opAnim = [CABasicAnimation animationWithKeyPath:@"opacity"]; opAnim.duration = 3.0; opAnim.fromValue = [NSNumber numberWithFloat:.25]; opAnim.toValue= [NSNumber numberWithFloat:1.0]; opAnim.cumulative = YES; opAnim.repeatCount = 2; [plane.layer addAnimation:opAnim forKey:@"animateOpacity"]; CGAffineTransform moveTransform = CGAffineTransformMakeTranslation(180, 200); CABasicAnimation *moveAnim = [CABasicAnimation animationWithKeyPath:@"transform"]; moveAnim.duration = 6.0; moveAnim.toValue= [NSValue valueWithCATransform3D: CATransform3DMakeAffineTransform(moveTransform)]; [plane.layer addAnimation:moveAnim forKey:@"animateTransform"];}
显式动画时候，不必定义CALayer的变化，也不必执行它们，而是通过CABasicAnimation逐个定义动画。其中每个动画都含有各自的duration、repeatCount等属性。然后，使用addAnimation:forKey:方法分别将每个动画应用到层中。
[CABasicAnimation animationWithKeyPath:@“opacity”]获得透明度动画对象，@“transform”是指定转换动画。
opAnim.cumulative 属性是指定累计
opAnim.repeatCount 重复执行次数
CATransform3DMakeAffineTransform函数是将仿射变换矩阵变成Core Animation使用的Transform3D类型的矩阵。
15.5 关键帧显式动画
eanimate_keyFrame关键代码：
#import#import @interface eanimateViewController : UIViewController { IBOutlet UIImageView *plane;}-(IBAction)movePlane:(id)sender;@end//-m-(IBAction)movePlane:(id)sender { CAKeyframeAnimation *opAnim = [CAKeyframeAnimation animationWithKeyPath:@"opacity"]; opAnim.duration = 6.0; opAnim.values =[NSArray arrayWithObjects: [NSNumber numberWithFloat:0.25], [NSNumber numberWithFloat:0.75], [NSNumber numberWithFloat:1.0], nil]; opAnim.keyTimes = [NSArray arrayWithObjects: [NSNumber numberWithFloat:0.0], [NSNumber numberWithFloat:0.5], [NSNumber numberWithFloat:1.0], nil]; [plane.layer addAnimation:opAnim forKey:@"animateOpacity"]; CGAffineTransform moveTransform = CGAffineTransformMakeTranslation(180, 200); CABasicAnimation *moveAnim = [CABasicAnimation animationWithKeyPath:@"transform"]; moveAnim.duration = 6.0; moveAnim.toValue= [NSValue valueWithCATransform3D: CATransform3DMakeAffineTransform(moveTransform)]; [plane.layer addAnimation:moveAnim forKey:@"animateTransform"]; }
animation.values是一个值的数组。
animation.keyTimes是一个每个帧片段持续的时间比例，取值范围0.0-1.0之间。
关键帧之路径实例BallSteps
#import#import @interface BallStepsViewController : UIViewController { UIButton *drawButton; UIImageView *imageView;}@property (nonatomic, retain) IBOutlet UIButton *drawButton;@property (nonatomic, retain) IBOutlet UIImageView *imageView;- (IBAction)drawStar:(id)sender;@end//--m#import "BallStepsViewController.h"@implementation BallStepsViewController@synthesize drawButton;@synthesize imageView;- (IBAction)drawStar:(id)sender { [drawButton setEnabled:NO]; CGMutablePathRef starPath = CGPathCreateMutable(); CGPathMoveToPoint(starPath,NULL,160.0f, 100.0f); CGPathAddLineToPoint(starPath, NULL, 100.0f, 280.0f); CGPathAddLineToPoint(starPath, NULL, 260.0, 170.0); CGPathAddLineToPoint(starPath, NULL, 60.0, 170.0); CGPathAddLineToPoint(starPath, NULL, 220.0, 280.0); CGPathCloseSubpath(starPath); CAKeyframeAnimation *animation = nil; animation = [CAKeyframeAnimation animationWithKeyPath:@"position"]; [animation setDuration:10.0f]; [animation setDelegate:self]; [animation setPath:starPath]; CFRelease(starPath); starPath = nil; [[imageView layer] addAnimation:animation forKey:@"position"];}- (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag { [drawButton setEnabled:YES];}- (void)dealloc { [drawButton release]; [imageView release]; [super dealloc];}@end
[CAKeyframeAnimation animationWithKeyPath:@“position”];创建一个position类型的关键帧动画。
关键帧动画中可以定义路径，把这些路径放入到CGMutablePathRef 中与CG中的很相似。
CGPathCloseSubpath(starPath);结束路径。
[animation setPath:starPath];设置路径。
[animation setDelegate:self];设置委托对象为本身，即回调方法 animationDidStop:finished:。
最后CFRelease(starPath);释放路径。
15.6 UIView级别动画
除了直接使用Core Animation 层实现动画，我们还有UIView直接实现隐式动画。
实例ViewAnimation：
@interface MainViewController : UIViewController { UIImageView *animImageView; UIButton *button;}@property (assign) IBOutlet UIImageView *animImageView;@property (assign) IBOutlet UIButton *button;- (IBAction)action:(id)sender;@end
//--m#import "MainViewController.h"@implementation MainViewController@synthesize animImageView;@synthesize button;- (IBAction)action:(id)sender { [UIView beginAnimations:@"Hide Button" context:nil]; [[self button] setAlpha:0.0]; [UIView commitAnimations]; [UIView beginAnimations:@"Slide Around" context:nil]; [UIView setAnimationDuration:1.0]; [UIView setAnimationDelegate:self]; [UIView setAnimationDidStopSelector:@selector(viewAnimationDone:)]; [UIView setAnimationRepeatCount:3]; [UIView setAnimationRepeatAutoreverses:YES]; CGPoint center = [[self animImageView] center]; center.y += 100; [[self animImageView] setCenter:center]; [UIView commitAnimations];}- (void)viewAnimationDone:(NSString*)name { [UIView beginAnimations:@"Show Button" context:nil]; [[self button] setAlpha:1.0]; [UIView commitAnimations];}@end UIView中的动画是在动画块中定义的，动画块是UIView beginAnimations:context:开始， 在UIView commitAnimations结束。
首先开始将按钮设置透明度为0的，结果是开始动画时候隐藏了。
然后，又开始新的动画中设置委托事件：
[UIView setAnimationDelegate:self]
[UIView setAnimationDidStopSelector:@selector(viewAnimationDone:)];
当动画结束的时候调用viewAnimationDone:方法。
内置UIView动画
UIView具有一个UIViewAnimationTransition属性可以设定动画，这些动画是iOS提供几个常用动画有：
UIViewAnimationTransitionNone
UIViewAnimationTransitionFlipFromLeft
UIViewAnimationTransitionFlipFromRight
UIViewAnimationTransitionCurlUp
UIViewAnimationTransitionCurlDown
实例UIViewAnimation
#import@interface UIViewAnimationViewController : UIViewController {}- (IBAction)doUIViewAnimation:(id)sender;@end//-m#import "UIViewAnimationViewController.h"@implementation UIViewAnimationViewController- (IBAction)doUIViewAnimation:(id)sender{ [UIView beginAnimations:@"animationID" context:nil]; [UIView setAnimationDuration:1.5f]; [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut]; [UIView setAnimationRepeatAutoreverses:NO]; UIButton *theButton = (UIButton *)sender; switch (theButton.tag) { case 1: [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:YES];//oglFlip, fromLeft break; case 2: [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES];//oglFlip, fromRight break; case 3: [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:self.view cache:YES]; break; case 4: [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES]; break; default: break; } //[self.view exchangeSubviewAtIndex:1 withSubviewAtIndex:0]; [UIView commitAnimations];}- (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil;}- (void)dealloc { [super dealloc];}@end
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut]设置动画曲线，动画曲线指定的是动画进入和退出的方式，它也有几个常量：
UIViewAnimationCurveEaseInOut
UIViewAnimationCurveEaseIn
UIViewAnimationCurveEaseOut
UIViewAnimationCurveLinear
setAnimationTransition: forView: cache:方法第一个参数定义动画类型，第二个参数是当前视图对象，第三个参数上使用缓冲区。