Easing - iOS Core Animation - page 222

Figure 10.4 A custom easing function, suitable for a clock tick
Listing 10.5 The Clock Program with Custom Easing Function Added
- ( void )setAngle:( CGFloat )angle
forHand:( UIView *)handView
animated:( BOOL )animated
{
//generate transform
CATransform3D transform = CATransform3DMakeRotation (angle, 0 , 0 , 1 );
if (animated)
{
//create transform animation
CABasicAnimation *animation = [ CABasicAnimation animation ];
animation. keyPath = @"transform" ;
animation. fromValue =
[handView. layer . presentationLayer valueForKey : @"transform" ];
animation. toValue = [ NSValue valueWithCATransform3D :transform];
animation. duration = 0.5 ;
animation. delegate = self ;
animation. timingFunction =
[ CAMediaTimingFunction functionWithControlPoints : 1 : 0 : 0.75 : 1 ];
//apply animation
handView. layer . transform = transform;
[handView. layer addAnimation :animation forKey : nil ];