用代码实现时钟功能

// 每一秒旋转的角度

#define perSec  6

// 每一分钟旋转的角度

#define perMin 6

// 每一个小时旋转的角度

#define perHour 30

// 每一分钟所对应时针旋转的角度

#define perMin2hourAngle 0.5

#import "ViewController.h"

@interface
ViewController ()

@property (weak,
nonatomic) IBOutlet
UIImageView *myView;

@property(nonatomic,
strong)CALayer *secLayer;

@property(nonatomic,
strong)CALayer *hourLayer;

@property(nonatomic,
strong)CALayer *minLayer;

@end

@implementation ViewController

- (void)viewDidLoad {

    [super
viewDidLoad];

    [self setUpSec];

    [self setUpMin];

    [self
setUpHour];

    

// 创建一个定时器

    [NSTimer
scheduledTimerWithTimeInterval:1
target:self
selector:@selector(timeChange)
userInfo:nil
repeats:YES];

    

    [self
timeChange];

}

- (void)timeChange

{

//    获取当前日历

    NSCalendar *calendar = [NSCalendar
currentCalendar];

//    获取当前日期单元

    NSDateComponents *cmp = [calendar
components:NSCalendarUnitHour|
NSCalendarUnitSecond|NSCalendarUnitMinute
fromDate:[NSDate
date]];

//    获取当前日期中的当前秒数

    NSInteger sec = cmp.second;

//    获取当前日期中的分钟数

    NSInteger min = cmp.minute;

//    获取当前日期中的小时数

    NSInteger hour = cmp.hour;

//    计算秒针走过的弧度

CGFloat secAngle =
perSec * sec /180.0 *M_PI;

//    计算分针走过的弧度

CGFloat minAngle =
perMin * min /180.0 *M_PI;

//    计算时针走过的弧度

CGFloat hourAngle = (perHour * hour+
perMin2hourAngle * min) /180.0 *M_PI ;

    

    self.secLayer.transform =
CATransform3DMakeRotation(secAngle,
0, 0, 1);

    self.minLayer.transform =
CATransform3DMakeRotation(minAngle,
0, 0, 1);

    self.hourLayer.transform =
CATransform3DMakeRotation(hourAngle,
0, 0, 1);

    

}

- (void)setUpSec

{

   
//    创建一个非根图层（秒针）

    CALayer *seclayer = [CALayer
layer];

    self.secLayer = seclayer;

    

    seclayer.backgroundColor = [UIColor
redColor].CGColor;

    seclayer.bounds =
CGRectMake(0,
0, 2, 80);

    seclayer.anchorPoint =
CGPointMake(0.5,
1);

    seclayer.position =
CGPointMake(self.myView.bounds.size.width
*0.5,
self.myView.bounds.size.height
*0.5);

    //   
把图层添加到根图层中

    [self.myView.layer
addSublayer:seclayer];

 

}

- (void)setUpMin

{

   
//    创建一个非根图层（秒针）

    CALayer *minlayer = [CALayer
layer];

    self.minLayer = minlayer;

    

    minlayer.backgroundColor = [UIColor
blackColor].CGColor;

    minlayer.bounds =
CGRectMake(0,
0, 3, 70);

    minlayer.anchorPoint =
CGPointMake(0.5,
1);

    minlayer.position =
CGPointMake(self.myView.bounds.size.width
*0.5,
self.myView.bounds.size.height
*0.5);

    //   
设置时针的圆角半径

    minlayer.cornerRadius =
1;

    //   
把图层添加到根图层中

    [self.myView.layer
addSublayer:minlayer];

}

- (void)setUpHour

{

   
//    创建一个非根图层（秒针）

    CALayer *hourlayer = [CALayer
layer];

    self.hourLayer = hourlayer;

    

    hourlayer.backgroundColor = [UIColor
blackColor].CGColor;

    hourlayer.bounds =
CGRectMake(0,
0, 4, 60);

    hourlayer.anchorPoint =
CGPointMake(0.5,
1);

    hourlayer.position =
CGPointMake(self.myView.bounds.size.width
*0.5,
self.myView.bounds.size.height
*0.5);

    //   
设置时针的圆角半径

    hourlayer.cornerRadius =
2;

    

    //   
把图层添加到根图层中

    [self.myView.layer
addSublayer:hourlayer];

}

@end