IOS利用旋轉實現時鐘

- (void)viewDidLoad {
    [super viewDidLoad];
    self.secondHand.layer.anchorPoint = CGPointMake(.5, .9);
    self.minuteHand.layer.anchorPoint = CGPointMake(.5, .9);
    self.hourHand.layer.anchorPoint = CGPointMake(.5, .9);
   
    self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(tick) userInfo:nil repeats:YES];
    [self tick];
}

- (void)tick {
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSUInteger units = NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
    NSDateComponents *components = [calendar components:units fromDate:[NSDate date]];
    CGFloat hoursAngle = (components.hour / 12.0) *M_PI * 2.0;
    CGFloat minsAngle = (components.minute / 60.0) * M_PI * 2.0;
    CGFloat secsAngle = (components.second / 60.0) * M_PI * 2.0;
   
    self.hourHand.transform = CGAffineTransformMakeRotation(hoursAngle);
    self.minuteHand.transform = CGAffineTransformMakeRotation(minsAngle);
    self.secondHand.transform = CGAffineTransformMakeRotation(secsAngle);

}