CABasicAnimation *animation=[CABasicAnimation animationWithKeyPath:@"opacity"];
 animation.delegate = self;
 animation.fromValue=[NSNumber numberWithFloat:1.0];
animation.toValue=[NSNumber numberWithFloat:0.0];
animation.autoreverses= NO;
animation.duration=2.0;
animation.repeatCount= 0;
animation.fillMode=kCAFillModeForwards;
animation.removedOnCompletion=NO;
[self.view.layer addAnimation:animation forKey:@"remove"];

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag {
    if (flag) {
        if (anim == [self.view.layer animationForKey:@"remove"]) {
            [self.view removeFromSuperview];
        }
    }
}

注意点:
1.如果[self.view.layer animationForKey:“key”]为null。加上self.view.layer.removedOnCompletion=NO这句话就可以了。就可以通过[self.view.layer animationForKey:@“key”];”查找到对应key的animation。

2.动画连续播放中间有闪现画面，不连续。
设置一下animation.fillMode = kCAFillModeForwards;就可以了