Animate UIView height from bottom to top

Question

I\'m doing a simple animation of UIView height so that it reveals.

By default it seems to be revealing from top to bottom, and I want it to reveal bottom to top.

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Answer 1

As requested, this is the code that I'm using... I'm using a CAKeyFrameAnimation, which may be a bit more than what you're looking for. It would probably work the same with a CABasicAnimation, I'm just showing you this code because I already have it written.

-(id)initWithFrame:(CGRect)frame {
  self = [super initWithFrame:frame];
  if (self) {   
    springLayer = [[CALayer alloc] init];
    springLayer.backgroundColor = [UIColor redColor].CGColor;
    springLayer.anchorPoint = CGPointMake(0, 1);
    springLayer.frame = CGRectMake(125, 285, 100, 115);
    [springLayer setNeedsDisplay];
    [self.layer addSublayer:springLayer];
    [self test];
  }
  return self;
}

-(void)test {
    CAKeyframeAnimation *heightAnim = [[CAKeyframeAnimation alloc] init];
    heightAnim.duration = 3;
    heightAnim.removedOnCompletion = NO;
    heightAnim.fillMode = kCAFillModeForwards;

    heightAnim.beginTime = CACurrentMediaTime() + 0.25;

    NSMutableArray *v = [[NSMutableArray alloc] init];
    NSMutableArray *t = [[NSMutableArray alloc] init];

    float dest = 250;
    float difference = 135;


    while (difference > 1.0) {
        [v addObject:[NSNumber numberWithFloat:dest-difference]];
        [t addObject:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut]];

        difference *= 0.7;

        [v addObject:[NSNumber numberWithFloat:dest+difference]];
        [t addObject:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut]];

        difference *= 0.7;
    }

    heightAnim.values = v;
    heightAnim.timingFunctions = t;

    [springLayer addAnimation:heightAnim forKey:@"bounds.size.height"];
}