Creating a Pop animation similar to the presentation of UIAlertView

Question

I would like to present a view in the same manner as that of UIAlertView - a pop/spring. Unfortunately subclassing UIAlertView is not an option for the view I need to presen

Answer 1

- (void) attachPopUpAnimation
{
    CAKeyframeAnimation *animation = [CAKeyframeAnimation
        animationWithKeyPath:@"transform"];

    CATransform3D scale1 = CATransform3DMakeScale(0.5, 0.5, 1);
    CATransform3D scale2 = CATransform3DMakeScale(1.2, 1.2, 1);
    CATransform3D scale3 = CATransform3DMakeScale(0.9, 0.9, 1);
    CATransform3D scale4 = CATransform3DMakeScale(1.0, 1.0, 1);

    NSArray *frameValues = [NSArray arrayWithObjects:
        [NSValue valueWithCATransform3D:scale1],
        [NSValue valueWithCATransform3D:scale2],
        [NSValue valueWithCATransform3D:scale3],
        [NSValue valueWithCATransform3D:scale4],
        nil];
    [animation setValues:frameValues];

    NSArray *frameTimes = [NSArray arrayWithObjects:
        [NSNumber numberWithFloat:0.0],
        [NSNumber numberWithFloat:0.5],
        [NSNumber numberWithFloat:0.9],
        [NSNumber numberWithFloat:1.0],
        nil];    
    [animation setKeyTimes:frameTimes];

    animation.fillMode = kCAFillModeForwards;
    animation.removedOnCompletion = NO;
    animation.duration = .2;

    [self.layer addAnimation:animation forKey:@"popup"];
}

Answer 2

the pointer to delackner's post is the best initial one i found as well. i would only offer for folks trying to really mimic UIAlertView a few things:

1. adding the rounded edges, border, and semi-transparent layer color
2. some alpha fade-in/-out, and
3. redoing with blocks as somewhat more succinct with latest iOS toolchain
4. i also found the initial 1.1 scale-out he suggests too large, 1.05 seemed more correct visually to me in most cases

Code:

self.layer.cornerRadius = 10.0;
[self.layer setMasksToBounds:YES];
self.layer.backgroundColor = [[UIColor blueColor] colorWithAlphaComponent:0.60].CGColor;
self.layer.borderColor = [UIColor whiteColor].CGColor;
self.layer.borderWidth = 1.1;
if (self.hidden == YES) { // swoop in if coming from hidden, otherwise pulse in-place
  self.transform = CGAffineTransformMakeScale(0.6, 0.6);
}
self.hidden = NO;
[UIView animateWithDuration:0.2
                 animations:^{
                   self.transform = CGAffineTransformMakeScale(1.05, 1.05);
                   self.alpha = 0.8;
                 }
                 completion:^(BOOL finished){
                   [UIView animateWithDuration:1/15.0
                                    animations:^{
                                      self.transform = CGAffineTransformMakeScale(0.9, 0.9);
                                      self.alpha = 0.9;
                                    }
                                    completion:^(BOOL finished) {
                                      [UIView animateWithDuration:1/7.5
                                                       animations:^{
                                                         self.transform = CGAffineTransformIdentity;                                                             
                                                         self.alpha = 1.0;
                                                       }
                                       ];
                                    }
                    ];
                 }
 ];

Answer 3

One thing: multi-step animations like this are much easier if you use a CAKeyframeAnimation instead of mutiple UIView queued animations.