layer動畫。

CABasicAnimation--對應android 屬性動畫。

  　　//透明動畫。
    CABasicAnimation * animation = [CABasicAnimation animationWithKeyPath:@"opacity"];

animation.beginTime = CACurrentMediaTime()+3;//開始時間

    animation.fromValue = @1.0;//開始值。
    animation.toValue = @0.1;//結束值 
    animation.duration = 2.0f
 
;//時長
    animation.fillMode = kCAFillModeBackwards;//填充模式
    self.myLabel.layer addAnimation:animation forKey:@"opacity" ];

可設定引數：1.時長。2反向播放3.開始時間 。4.重複次數。5.重複播放間隔。6.快慢。7.播完後行為。留在那裡還是移除。

/* The begin time of the object, in relation to its parent object, if
 * applicable. Defaults to 0. */

@property CFTimeInterval beginTime;
從什麼時候開始執行動畫。
 
/* The basic duration of the object. Defaults to 0. */
//動畫時長
@property CFTimeInterval duration;

/* The rate of the layer. Used to scale parent time to local time, e.g.
 * if rate is 2, local time progresses twice as fast as parent time.
 * Defaults to 1. */
//執行時，相對速度。
@property float speed;

/* Additional offset in active local time. i.e. to convert from parent
 * time tp to active local time t: t = (tp - begin) * speed + offset.
 * One use of this is to "pause" a layer by setting `speed' to zero and
 * `offset' to a suitable value. Defaults to 0. 
 
*/

@property CFTimeInterval timeOffset;

/* The repeat count of the object. May be fractional. Defaults to 0. */

@property float repeatCount;//重複次數

/* The repeat duration of the object. Defaults to 0. */

@property CFTimeInterval repeatDuration;//多入後重播。

/* When true, the object plays backwards after playing forwards. Defaults
 * to NO. */

@property BOOL autoreverses;//自動反向播放

/* Defines how the timed object behaves outside its active duration.
 * Local time may be clamped to either end of the active duration, or
 * the element may be removed from the presentation. The legal values
 * are `backwards', `forwards', `both' and `removed'. Defaults to
 * `removed'. */

@property(copy) CAMediaTimingFillMode fillMode;//填充模式

@end

/* `fillMode' options. */

CA_EXTERN CAMediaTimingFillMode const kCAFillModeForwards//執行填充。動畫結束在哪兒就在哪兒。必須是不移除動畫。
    API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0));
CA_EXTERN CAMediaTimingFillMode const kCAFillModeBackwards//執行前就填充到相應位置或狀態。
    API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0));
CA_EXTERN CAMediaTimingFillMode const kCAFillModeBoth
    API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0));
CA_EXTERN CAMediaTimingFillMode const kCAFillModeRemoved
    API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0));

基本和android 一樣一樣的。