IOS利用旋转实现时钟

– (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);

}