#import "ViewController.h" @interface ViewController ()@property(nonatomic,strong)CALayer *calayer;@end @implementation ViewController - (void)viewDidLoad {    [super viewDidLoad];    UIButton *btn =[UIButton buttonWithType:UIButtonTypeSystem];    btn.frame=CGRectMake(100, 100, 100, 50) ;    btn.tag=1;    [btn setTitle:@"隐式事务按钮" forState:UIControlStateNormal];    [btn setTitleColor:[UIColor redColor] forState:UIControlStateNormal];    [btn setTintColor:[UIColor blackColor]];    [btn addTarget:self action:@selector(btnclick:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:btn];         UIButton *btn1 =[UIButton buttonWithType:UIButtonTypeSystem];    btn1.frame=CGRectMake(200, 100, 100, 50) ;    btn1.tag=2;    [btn1 setTitle:@"显式事务按钮" forState:UIControlStateNormal];    [btn1 setTitleColor:[UIColor redColor] forState:UIControlStateNormal];    [btn1 setTintColor:[UIColor blackColor]];    [btn1 addTarget:self action:@selector(btnclick:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:btn1];    //    CATransaction 事务类,可以对多个layer的属性同时进行修改.它分隐式事务,和显式事务.//    区分隐式动画和隐式事务：隐式动画通过隐式事务实现动画 。修改Calayer的属性属于隐式事务//    区分显式动画和显式事务：显式动画有多种实现方式，显式事务是一种实现显式动画的方式。     //隐式事务    self.calayer=[CALayer layer];    self.calayer.bounds=CGRectMake(150, 150, 100, 100);    self.calayer.position=CGPointMake(100, 200);    self.calayer.backgroundColor=[UIColor redColor].CGColor;    self.calayer.borderColor = [UIColor blackColor].CGColor;    self.calayer.opacity = 1.0f;    [self.view.layer addSublayer:self.calayer];    [super viewDidLoad]; }-(void)btnclick:(id)sender{    UIButton *btn=(UIButton *)sender;    if (btn.tag==1) {        [CATransaction setDisableActions:YES];        self.calayer.cornerRadius = (self.calayer.cornerRadius == 0.0f) ? 30.0f : 0.0f;        self.calayer.opacity = (self.calayer.opacity == 1.0f) ? 0.5f : 1.0f;    }    else    {        //事务嵌套        [CATransaction begin];        [CATransaction begin];        [CATransaction setDisableActions:YES];        self.calayer.opacity = (self.calayer.opacity == 1.0f) ? 0.5f : 1.0f;        [CATransaction commit];        //上面的动画并不会立即执行，需要等最外层的commit        [NSThread sleepForTimeInterval:3];        //显式事务默认开启动画效果,kCFBooleanTrue关闭        [CATransaction setValue:(id)kCFBooleanFalse                         forKey:kCATransactionDisableActions];        //动画执行时间        [CATransaction setValue:[NSNumber numberWithFloat:10.0f] forKey:kCATransactionAnimationDuration];        //[CATransaction setAnimationDuration:[NSNumber numberWithFloat:5.0f]];        self.calayer.cornerRadius = (self.calayer.cornerRadius == 0.0f) ? 30.0f : 0.0f;        [CATransaction commit];             }     }- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.} @end