iOS实现简单时钟效果

//将旋转角度转换为弧度制
#define angleToRadion(angle) ((angle) / 180.0 * M_PI)

//秒针每秒钟转过的角度
#define perSecondAngle 6
//分针每分钟转过的角度
#define perMinuteAngle 6
//时针每小时转过的角度
#define perHourAngle 30
//时针每分钟转过的角度
#define perMuniteHourAngle 0.5

#define kClockWidth 300
#define kClockHeight 250

@interface ViewController ()

//底盘
@property (weak, nonatomic) IBOutlet UIImageView *imgView;

@property (nonatomic, weak) CALayer *secondLayer;//秒
@property (nonatomic, weak) CALayer *minuteLayer;//分
@property (nonatomic, weak) CALayer *hourLayer;//时

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //时钟
    [self setUpHourLayer];
    
    //分钟
    [self setUpMinuteLayer];
    
    //秒钟
    [self setUpSecondLayer];
    
    //创建定时器
    [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(timeChange) userInfo:nil repeats:YES];
    
}

- (void)setUpHourLayer
{
    //创建图层
    CALayer *layer = [CALayer layer];
    layer.backgroundColor = [UIColor blackColor].CGColor;
    layer.cornerRadius = 8;
    
    //设置图层的锚点
    layer.anchorPoint = CGPointMake(0.5, 1);
    //设置图层的位置和尺寸
    layer.position = CGPointMake(kClockWidth * 0.5, kClockHeight * 0.5);
    layer.bounds = CGRectMake(0, 0, 5, kClockWidth * 0.5 - 44);
    
    //将图层添加到父图层中
    [self.imgView.layer addSublayer:layer];
    self.hourLayer = layer;
}

- (void)setUpMinuteLayer
{
    CALayer *layer = [CALayer layer];
    layer.backgroundColor = [UIColor blackColor].CGColor;
    layer.cornerRadius = 4;
    
    //设置锚点
    layer.anchorPoint = CGPointMake(0.5, 1);
    
    //设置位置和尺寸
    layer.position = CGPointMake(kClockWidth * 0.5, kClockHeight * 0.5);
    layer.bounds = CGRectMake(0, 0, 3, kClockWidth * 0.5 - 34);
    
    //将图层添加到父图层中
    [self.imgView.layer addSublayer:layer];
    self.minuteLayer = layer;
}

- (void)setUpSecondLayer
{
    CALayer *layer = [CALayer layer];
    layer.backgroundColor = [UIColor redColor].CGColor;
    
    //设置锚点
    layer.anchorPoint = CGPointMake(0.5, 1);
    
    //设置位置和尺寸
    layer.position = CGPointMake(kClockWidth * 0.5, kClockHeight * 0.5);
    layer.bounds = CGRectMake(0, 0, 1, kClockWidth * 0.5 - 24);
    
    //将图层添加到父图层中
    [self.imgView.layer addSublayer:layer];
    self.secondLayer = layer;
}

- (void)timeChange
{
    //获取日历对象
    NSCalendar *calendar = [NSCalendar currentCalendar];
    //NSLog(@"calendar = %",calendar);
    
    //获取日期组件
    NSDateComponents *components = [calendar components:NSCalendarUnitSecond | NSCalendarUnitMinute | NSCalendarUnitHour fromDate:[NSDate date]];
    
    //获取当前的时分秒值
    NSInteger second = components.second;
    NSInteger munite = components.minute;
    NSInteger hour = components.hour;
    
    //计算当前时分秒表针转过的角度（弧度制）
    CGFloat secondAngle = angleToRadion(second * perSecondAngle);
    CGFloat muniteAngle = angleToRadion(munite * perMinuteAngle);
    CGFloat hourAngle = angleToRadion(hour *perHourAngle + munite * perMuniteHourAngle);
    
    //修改时分秒表针位于的图层的transform属性，执行隐式动画
    self.secondLayer.transform = CATransform3DMakeRotation(secondAngle, 0, 0, 1);
    self.minuteLayer.transform = CATransform3DMakeRotation(muniteAngle, 0, 0, 1);
    self.hourLayer.transform = CATransform3DMakeRotation(hourAngle, 0, 0, 1);

}
@end