#import "ViewController.h"#import <QuartzCore/QuartzCore.h>@interface ViewController (){    //时针    UIImageView *m_s;    //分针    UIImageView *m_f;    //秒针    UIImageView *m_m;}@end@implementation ViewController- (void)viewDidLoad{    [super viewDidLoad];        m_s = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"s"]];    m_s.frame = CGRectMake(0, 0, 20, 90);    m_f = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"f"]];     m_f.frame = CGRectMake(0, 0, 20, 100);    m_m = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"m"]];     m_m.frame = CGRectMake(0, 0, 20, 130);    CALayer *blueLayer = [[CALayer alloc] init];    blueLayer.frame = CGRectMake(10, 20, 300, 400);    blueLayer.backgroundColor = [UIColor blueColor].CGColor;//    把blueLayer的contents属性设置成图片。//    contents    /* An object providing the contents of the layer, typically a CGImageRef,     * but may be something else. (For example, NSImage objects are     * supported on Mac OS X 10.6 and later.) Default value is nil.     * Animatable.          *对象提供该层的内容，一个典型的cgimageref，     *但可能是别的东西。（例如，nsimage对象     *后来支持在MAC OS X 10.6和默认值是零。）。     *动画。*/    UIImage *image = [UIImage imageNamed:@"b"];    blueLayer.contents = (__bridge id)(image.CGImage);        /*     CALayer与contentMode对应的属性叫做contentsGravity，但是它是一个NSString类型，而不是像对应的UIKit部分，那里面的值是枚举。contentsGravity可选的常量值有以下一些：          kCAGravityCenter     kCAGravityTop     kCAGravityBottom     kCAGravityLeft     kCAGravityRight     kCAGravityTopLeft     kCAGravityTopRight     kCAGravityBottomLeft     kCAGravityBottomRight     kCAGravityResize     kCAGravityResizeAspect     kCAGravityResizeAspectFill          和cotentMode一样，contentsGravity的目的是为了决定内容在图层的边界中怎么对齐，我们将使用kCAGravityResizeAspect，它的效果等同于UIViewContentModeScaleAspectFit， 同时它还能在图层中等比例拉伸以适应图层的边界。     */    blueLayer.contentsGravity = kCAGravityCenter;    //    当用代码的方式来处理寄宿图的时候，一定要记住要手动的设置图层的contentsScale属性，否则，你的图片在Retina设备上就显示得不正确啦。代码如下：        blueLayer.contentsScale = [UIScreen mainScreen].scale;        //    UIView有一个叫做clipsToBounds的属性可以用来决定是否显示超出边界的内容，    //CALayer对应的属性叫做masksToBounds，把它设置为YES，图片就在边界里了    blueLayer.masksToBounds = YES;    //    [self addSpriteImage:image withContentRect:CGRectMake(0, 0, 1, 1) Layer:blueLayer];    //    blueLayer.contentsCenter = CGRectMake(0.25, 0.25, .5, .5);    //    self.view.transform = CGAffineTransformMakeRotation(.5);        [self.view.layer addSublayer:blueLayer];        m_s.center = CGPointMake(blueLayer.position.x , blueLayer.position.y);    m_f.center = CGPointMake(blueLayer.position.x  , blueLayer.position.y);    m_m.center = CGPointMake(blueLayer.position.x  , blueLayer.position.y);    m_s.layer.anchorPoint = CGPointMake(.5, .9);    m_f.layer.anchorPoint = CGPointMake(.5, .9);    m_m.layer.anchorPoint = CGPointMake(.5, .9);    [self.view addSubview:m_s];    [self.view addSubview:m_f];    [self.view addSubview:m_m];    [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(tick) userInfo:nil repeats:YES];    //set initial hand positions    [self tick]; }- (void)tick{    //convert time to hours, minutes and seconds    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;    //calculate hour hand angle //calculate minute hand angle    CGFloat minsAngle = (components.minute / 60.0) * M_PI * 2.0;    //calculate second hand angle    CGFloat secsAngle = (components.second / 60.0) * M_PI * 2.0;    //rotate hands    m_s.transform = CGAffineTransformMakeRotation(hoursAngle);    m_f.transform = CGAffineTransformMakeRotation(minsAngle);    m_m.transform = CGAffineTransformMakeRotation(secsAngle);}/*! *  @Author Yunis_song, 15-01-07 16:01:51 * *  @brief  加载图片切割尺寸，只加载自己想要的部分 * *  @param image 图片 *  @param rect  加载图片剪裁信息 *  @param layer 图片加载到哪里 */- (void)addSpriteImage:(UIImage *)image withContentRect:(CGRect)rect Layer:(CALayer *)layer //set image{    layer.contents = (__bridge id)image.CGImage;        //scale contents to fit    layer.contentsGravity = kCAGravityResizeAspect;        //set contentsRect    //CGRectMake(x, y, w, h) 加载图片位置    //x 加载图片其实x坐标  值：0-1，相对位置  0 起始点  0.5 一半起始点    //y 加载图片其实y坐标  值：0-1，相对位置  0 起始点  0.5 一半起始点    //w 宽度  值：0-1 1加载全部  0.5 加载一般宽度    //h 高度  值：0-1 1加载全部  0.5 加载一般高度    layer.contentsRect = rect;}- (void)didReceiveMemoryWarning{    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end