Explicit Animations - iOS Core Animation - page 174

}
- ( void )tick
{
[ self updateHandsAnimated : YES ];
}
- ( void )updateHandsAnimated:( BOOL )animated
{
//convert time to hours, minutes and seconds
NSCalendar *calendar =
[[ NSCalendar alloc ] initWithCalendarIdentifier : NSGregorianCalendar ];
NSUInteger units = NSHourCalendarUnit |
NSMinuteCalendarUnit |
NSSecondCalendarUnit ;
NSDateComponents *components = [calendar components :units
fromDate: [ NSDate date ]];
//calculate hour hand angle
CGFloat hourAngle = (components. hour / 12.0 ) * M_PI * 2.0 ;
//calculate minute hand angle
CGFloat minuteAngle = (components. minute / 60.0 ) * M_PI * 2.0 ;
//calculate second hand angle
CGFloat secondAngle = (components. second / 60.0 ) * M_PI * 2.0 ;
//rotate hands
[ self setAngle :hourAngle forHand : self .hourHand animated :animated];
[ self setAngle :minuteAngle forHand : self .minuteHand animated :animated];
[ self setAngle :secondAngle forHand : self .secondHand animated :animated];
}
- ( 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 ];