CALayer 图层

// CALayer 图层属性，继承UIView都有该属性，可设置边框宽度、颜色、圆角、阴影等

UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(100, 100, 200, 150)];

imageView.image = [UIImage imageNamed:@"test.jpg"];

// 边框宽度、颜色

imageView.layer.borderWidth = 5;

imageView.layer.borderColor = [UIColor redColor].CGColor;

// 边框圆角

imageView.layer.cornerRadius = 20;

// 边框圆角超出部分隐藏 设置该属性后，阴影设置无效

//    imageView.layer.masksToBounds = YES;

// 阴影

imageView.layer.shadowColor = [UIColor blackColor].CGColor;

imageView.layer.shadowOffset = CGSizeMake(5, 5);

imageView.layer.shadowOpacity = 0.5;

[self.view addSubview:imageView];

// CALayer 创建、显示

// 比较UIView,CALayer不能处理事件，更加轻量级

CALayer *newLayer = [CALayer layer]; // 创建

newLayer.bounds = CGRectMake(100, 330, 200, 150); // 位置 必须设置

newLayer.position = CGPointMake(100, 330); // 位置 必须设置

// anchorPoint 定义的是CALayer中的点定在position位置 0-1,默认(0.5,0.5)是中心点 (0,0)是左上顶点 （1,1）右下点

newLayer.anchorPoint = CGPointMake(0, 0.5);

newLayer.contents = (id)[UIImage imageNamed:@"test.jpg"].CGImage;

newLayer.borderColor = [UIColor blackColor].CGColor;

newLayer.borderWidth = 5;

newLayer.cornerRadius = 10;

newLayer.masksToBounds = YES;

[self.view.layer addSublayer:newLayer];