在ios中运用core animation暂停和继续动画

 <pre name="code" class="cpp">//暂停layer上面的动画
 - (void)pauseLayer:(CALayer*)layer
 {
     CFTimeInterval pausedTime = [layer convertTime:CACurrentMediaTime() fromLayer:nil];
     layer.speed = 0.0;
     layer.timeOffset = pausedTime;
 }

 //继续layer上面的动画
 - (void)resumeLayer:(CALayer*)layer
 {
     CFTimeInterval pausedTime = [layer timeOffset];
     layer.speed = 1.0;
     layer.timeOffset = 0.0;
     layer.beginTime = 0.0;
     CFTimeInterval timeSincePause = [layer convertTime:CACurrentMediaTime() fromLayer:nil] - pausedTime;
     layer.beginTime = timeSincePause;
 }</pre><br>
 <pre></pre>
 <p>附上完整代码</p>
 <p></p>
 <p class="p1">AnimationPauseViewController.h</p>
 <pre name="code" class="cpp">#import <UIKit/UIKit.h>

 @interface AnimationPauseViewController : UIViewController {

     UIImageView *soccer;
     BOOL isPause;
     UIButton *controlButton;
 }
 @property (nonatomic, retain) IBOutlet UIImageView *soccer;
 - (IBAction)clickControlButton:(id)sender;
 @property (nonatomic, retain) IBOutlet UIButton *controlButton;

 @end</pre><br>
 <p></p>
 <p class="p1">AnimationPauseViewController.m</p>
 <p></p><pre name="code" class="cpp">#import "AnimationPauseViewController.h"
 #import <QuartzCore/QuartzCore.h>

 @implementation AnimationPauseViewController
 @synthesize controlButton;
 @synthesize soccer;

 - (void)dealloc
 {
     [soccer release];
     [controlButton release];
     [super dealloc];
 }

 - (void)didReceiveMemoryWarning
 {
     // Releases the view if it doesn't have a superview.
     [super didReceiveMemoryWarning];

     // Release any cached data, images, etc that aren't in use.
 }

 - (void)addAnimations
 {
     //让足球来回移动
     CABasicAnimation *translation = [CABasicAnimation animationWithKeyPath:@"position"];
     translation.fromValue = [NSValue valueWithCGPoint:CGPointMake(24, 240)];
     translation.toValue = [NSValue valueWithCGPoint:CGPointMake(320- 24, 240)];
     translation.duration = 2;
     translation.repeatCount = HUGE_VALF;
     translation.autoreverses = YES;

     //让足球来回转动
     CABasicAnimation *rotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
     //kCAMediaTimingFunctionLinear 表示时间方法为线性，使得足球匀速转动
     rotation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
     rotation.toValue = [NSNumber numberWithFloat:4 * M_PI];
     rotation.duration = 2;
     rotation.repeatCount = HUGE_VALF;
     rotation.autoreverses = YES;

     [soccer.layer addAnimation:rotation forKey:@"rotation"];
     [soccer.layer addAnimation:translation forKey:@"translation"];
 }

 #pragma mark - View lifecycle
 - (void)viewDidLoad
 {
     [super viewDidLoad];
     [self addAnimations];
 }


 - (void)viewDidUnload
 {
     [self setSoccer:nil];
     [self setControlButton:nil];
     [super viewDidUnload];
 }

 - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
 {
     // Return YES for supported orientations
     return (interfaceOrientation == UIInterfaceOrientationPortrait);
 }

 //暂停layer上面的动画
 - (void)pauseLayer:(CALayer*)layer
 {
     CFTimeInterval pausedTime = [layer convertTime:CACurrentMediaTime() fromLayer:nil];
     layer.speed = 0.0;
     layer.timeOffset = pausedTime;
 }

 //继续layer上面的动画
 - (void)resumeLayer:(CALayer*)layer
 {
     CFTimeInterval pausedTime = [layer timeOffset];
     layer.speed = 1.0;
     layer.timeOffset = 0.0;
     layer.beginTime = 0.0;
     CFTimeInterval timeSincePause = [layer convertTime:CACurrentMediaTime() fromLayer:nil] - pausedTime;
     layer.beginTime = timeSincePause;
 }

 - (void)pauseSoccer
 {
     isPause = YES;
     [controlButton setTitle:@"继续" forState:UIControlStateNormal];
     [self pauseLayer:soccer.layer];
 }

 - (void)resumeSoccer
 {
     isPause = NO;
     [controlButton setTitle:@"暂停" forState:UIControlStateNormal];
     [self resumeLayer:soccer.layer];
 }

 - (IBAction)clickControlButton:(id)sender {
     if (isPause) {
         [self resumeSoccer];
     }else{
         [self pauseSoccer];
     }
 }
 @end</pre><br>
 <br>
 <p></p>