类uialertview弹出动画

CAKeyframeAnimation * animation;
animation = [CAKeyframeAnimation animationWithKeyPath:@"transform"];
animation.duration = 0.5;
animation.delegate = self;
animation.removedOnCompletion = YES;
animation.fillMode = kCAFillModeForwards;

NSMutableArray *values = [NSMutableArray array];
[values addObject:[NSValue valueWithCATransform3D:CATransform3DMakeScale(0.1, 0.1, 1.0)]];
[values addObject:[NSValue valueWithCATransform3D:CATransform3DMakeScale(1.2, 1.2, 1.0)]];
[values addObject:[NSValue valueWithCATransform3D:CATransform3DMakeScale(0.9, 0.9, 0.9)]];
[values addObject:[NSValue valueWithCATransform3D:CATransform3DMakeScale(1.0, 1.0, 1.0)]];
animation.values = values;
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];

[_backView.layer addAnimation:animation forKey:nil];