1     //设置圆形cornerRadius，是宽或高的一半
 2 
 3     _imageView.layer.masksToBounds = YES;
 4 
 5     
 6 
 7     CGFloat w = _imageView.frame.size.width / 2;
 8 
 9     _imageView.layer.cornerRadius = w;
10 
11     
12 
13     //设置边框宽度及颜色
14 
15     [_imageView.layersetBorderWidth:2];
16 
17     [_imageView.layersetBorderColor:[[UIColorwhiteColor]CGColor]];
18 
19     
20 
21     //圆角设置(cornerRadius = 125，我用的图片是250*250，250的一半：125)
22 
23     _imageView.layer.cornerRadius = 125;
24 
25     _imageView.layer.masksToBounds = YES;
26 
27     
28 
29     //自动适应，保持图片宽高比
30 
31     _imageView.contentMode = UIViewContentModeScaleAspectFit;