UIImage *image = [UIImage imageNamed:@"资源中图片的名字"];

//图片的宽宽高
CGFloat imageWH = image.size.width;
//边界的宽度
CGFloat border = 1;
//背景区域的宽高
CGFloat ovalWH = imageWH + 2 * border;

//设置图形上下文的尺寸
CGSize size = CGSizeMake(ovalWH, ovalWH);
//开启图形上下文
UIGraphicsBeginImageContextWithOptions(size, NO, 0);

//绘制封闭的圆形路径
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, ovalWH, ovalWH)];
//设置填充颜色
[[UIColor blueColor] set];
//渲染所绘制的区域
[path fill];

//绘制封闭的圆形区域
UIBezierPath *clipPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(border, border, imageWH, imageWH)];
//设置超出区域的内容剪掉（不显示）
[clipPath addClip];
//见图片绘制到圆形区域内，从点(border, border)开始
[image drawAtPoint:CGPointMake(border, border)];

UIImage *clipImage = UIGraphicsGetImageFromCurrentImageContext();

self.imageView.image = clipImage;

UIGraphicsEndImageContext();