CALayer的使用

- (void)viewDidLoad {

    [super viewDidLoad];

    UIView *containerView = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 100, 3)];

    containerView.backgroundColor = [UIColor redColor];

    [self.view addSubview:containerView];

    //修改该容器layer的相关值

//    containerView.layer.frame = CGRectMake(0, 0, 200, 200);

//    containerView.layer.backgroundColor = [UIColor greenColor].CGColor;

    //创建一个独立的layer

    self.layer = [CALayer layer];

    //刚开始的进度为0

    self.layer.frame = CGRectMake(0, 0, 20, 3);

    self.layer.backgroundColor = [UIColor greenColor].CGColor;

    [containerView.layer addSublayer:self.layer];

    [self performSelector:@selector(layerAnimation) withObject:nil afterDelay:3.0];

}

- (void)layerAnimation {

    NSLog(@"修改了layer的frame值");

    //执行了隐式动画

    self.layer.frame = CGRectMake(0, 0, 100, 3);

    self.layer.backgroundColor = [UIColor blackColor].CGColor;

}