CALayer的基本属性和contexts的内容 即添加图片

CALayer *superLayer=self.view.layer;
    //创建CALayer
    CALayer *subLayer =[CALayer layer];
    //添加到父图层
    [superLayer addSublayer:subLayer];
    //尺寸
    subLayer.bounds =CGRectMake(0, 0, 200, 200);
    //颜色
    subLayer.backgroundColor =[UIColor greenColor].CGColor;
    //位置
    subLayer.position=CGPointMake(100, 100);
    //锚点
    subLayer.anchorPoint =CGPointMake(0 , 0);
    //圆角
    subLayer.cornerRadius =100;
    //context内容
    UIImage *image =[UIImage imageNamed:@"b"];
    subLayer.contents =(__bridge id)(image.CGImage);
    //边界剪裁
    subLayer.masksToBounds =YES;