view放大再缩小的动画

CABasicAnimation *animationZoomIn=[CABasicAnimation animationWithKeyPath:@"transform.scale"];
       //   roAnim.fromValue = [NSNumber numberWithFloat:0];
        animationZoomIn.duration=0.5f;
        
        animationZoomIn.autoreverses=NO;
        
        animationZoomIn.repeatCount=0;
        
        animationZoomIn.fromValue = [NSNumber numberWithFloat:0.5f];
        animationZoomIn.toValue=[NSNumber numberWithFloat:1.0f];
        
        animationZoomIn.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
        
        animationZoomIn.removedOnCompletion = NO;
        animationZoomIn.fillMode = kCAFillModeBoth;
        
        
        [controller.navigationController.view.layer addAnimation:animationZoomIn forKey:nil];
        
        [[controller navigationController] pushViewController:tweetView animated:FALSE];