使用CALayer 实现时钟的展示

代码

主要视图结构：

@property (weak, nonatomic) IBOutlet UIImageView *clockView;
@property (weak,nonatomic) CALayer *secondLayer;
@property (weak,nonatomic) CALayer *minuteLayer;
@property (weak,nonatomic) CALayer *hourLayer;

主要代码实现

- (void)viewDidLoad {
    [super viewDidLoad];
    [self layerRotation];
    //开启定时器
    [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(layerRotation) userInfo:nil repeats:YES];

}
#pragma mark - 秒针旋转
- (void)layerRotation {
    //获取秒数
    NSCalendar *calendar = [NSCalendar currentCalendar];//获取日历对象
    NSDateComponents *components = [calendar components:NSCalendarUnitSecond| NSCalendarUnitHour|NSCalendarUnitMinute  fromDate:[NSDate date]];
    CGFloat second = components.second;
    //计算当前的秒针对应的弧度
    CGFloat secondAngle = second *KHSPerSecondAngle;
    //1、旋转秒针
    [self.secondLayer setTransform:CATransform3DMakeRotation(angle2radian(secondAngle), 0, 0, 1)];
    //KVC--有bug
//    [self.secondLayer setValue:@angle2radian(secondAngle) forKeyPath:@"transform.rotation"];
    //2、旋转分针
    CGFloat minute = components.minute;
    CGFloat minuteAngle = minute *KHSPerMinuteAngle +second*(KHSPerMinuteAngle/60.0);//整分＋秒的弧度(每秒对应的0.1弧度)
    [self.minuteLayer setTransform:CATransform3DMakeRotation(angle2radian(minuteAngle), 0, 0, 1)];
    //3、旋转时针
    CGFloat hour = components.hour;
    //计算当前的秒针对应的弧度
    CGFloat hourAngle = hour *KHSPerHourAngle + minute*(KHSPerHourAngle/60.0) +second*(KHSPerHourAngle/360.0);//整点的角度＋分钟的角度+秒的弧度（2分钟＝1弧度＝》1个小时＝30弧度）
    [self.hourLayer setTransform:CATransform3DMakeRotation(angle2radian(hourAngle), 0, 0, 1)];
}