CABasicAnimation - tilt into background (a la National Geographic Park Guides)

gistfile1.m

- (void)dropItBack:(id)sender
{
  // Position
  CABasicAnimation *posAnimation = [CABasicAnimation animationWithKeyPath:@"position"];
  posAnimation.toValue = [NSValue valueWithCGPoint:CGPointMake(self.center.x, self.center.y - 50.f)];
  
  // Opacity
  CABasicAnimation *opacityAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
  opacityAnimation.toValue = [NSNumber numberWithFloat:0.5f];

  CABasicAnimation *scaleAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
  scaleAnimation.toValue = [NSNumber numberWithDouble:0.8];

  // Dramaticism of the Z rotation
  // A lower number is more dramatic
  float distance = 1000;
  CATransform3D trans = CATransform3DIdentity;
  trans.m34 = 1.f / -distance;
  
  // Rotate Back
  CABasicAnimation *rockBack = [CABasicAnimation animationWithKeyPath:@"transform"];
  rockBack.toValue = [NSValue valueWithCATransform3D:CATransform3DRotate(trans, M_PI_4, 1.f, 0.f, 0.f)];
  rockBack.beginTime = 0.f;
    
  // Rotate forward
  trans.m34 = 0.f;
  CABasicAnimation *rockForward = [CABasicAnimation animationWithKeyPath:@"transform"];
  rockForward.toValue = [NSValue valueWithCATransform3D:CATransform3DRotate(trans, M_PI_4, -1.f, 0.f, 0.f)];
  rockForward.beginTime = 0.25f;

  CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
  animationGroup.duration = 0.5f;
  animationGroup.repeatCount = 0.f;
  animationGroup.removedOnCompletion = NO;
  animationGroup.autoreverses = NO;
  animationGroup.fillMode = kCAFillModeForwards;
  animationGroup.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
  [animationGroup setAnimations:[NSArray arrayWithObjects:rockBack, rockForward, scaleAnimation, posAnimation, opacityAnimation, nil]];
  
  [self.layer addAnimation:animationGroup forKey:nil];
}

- (void)bringItForward:(id)sender
{
  // Position
  CABasicAnimation *posAnimation = [CABasicAnimation animationWithKeyPath:@"position"];
  posAnimation.toValue = [NSValue valueWithCGPoint:self.center];
  
  // Opacity
  CABasicAnimation *opacityAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
  opacityAnimation.toValue = [NSNumber numberWithFloat:1.f];
    
  // Scale
  CABasicAnimation *scaleAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
  scaleAnimation.toValue = [NSNumber numberWithDouble:1.f];

  // Dramaticism of the Z rotation
  // A lower number is more dramatic
  float distance = 1000;
  CATransform3D trans = CATransform3DIdentity;
  trans.m34 = 1.f / distance;
  
  // Rotate back
  CABasicAnimation *rockBack = [CABasicAnimation animationWithKeyPath:@"transform"];
  rockBack.toValue = [NSValue valueWithCATransform3D:CATransform3DRotate(trans, M_PI_4, 1.f, 0.f, 0.f)];
  rockBack.beginTime = 0.f;
  
  // Rotate forward
  trans.m34 = 0.f;
  CABasicAnimation *rockForward = [CABasicAnimation animationWithKeyPath:@"transform"];
  rockForward.toValue = [NSValue valueWithCATransform3D:CATransform3DRotate(trans, M_PI_4, -1.f, 0.f, 0.f)];
  rockForward.beginTime = 0.25f;
  
  CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
  animationGroup.duration = 0.5f;
  animationGroup.repeatCount = 0.f;
  animationGroup.removedOnCompletion = NO;
  animationGroup.autoreverses = NO;
  animationGroup.fillMode = kCAFillModeForwards;
  animationGroup.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
  [animationGroup setAnimations:[NSArray arrayWithObjects:posAnimation, rockBack, rockForward, opacityAnimation, nil]];
  
  [self.layer addAnimation:animationGroup forKey:nil];
}