- (void)viewDidLoad {
  [super viewDidLoad];
   
  //加载图片
  UIImage *image = [UIImage imageNamed:@"菲哥"];
   
  //获取图片尺寸
  CGSize size = image.size;
   
  //开启位图上下文
  UIGraphicsBeginImageContextWithOptions(size, NO, 0);
   
  //创建圆形路径
  UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, image.size.width, image.size.height)];
   
  //设置为裁剪区域
  [path addClip];
   
  //绘制图片
  [image drawAtPoint:CGPointZero];
   
  //获取裁剪后的图片
  _imageView.image = UIGraphicsGetImageFromCurrentImageContext();
   
  //关闭上下文
  UIGraphicsEndImageContext();
   
}

- (void)viewDidLoad {
  [super viewDidLoad];
   
  //加载图片
  UIImage *image = [UIImage imageNamed:@"大菲哥"];
   
  //设置边框宽度
  CGFloat border = 3;
  CGFloat imageWH = image.size.width;
   
  //计算外圆的尺寸
  CGFloat ovalWH = imageWH + 2 * border;
   
  //开启上下文
  UIGraphicsBeginImageContextWithOptions(image.size, NO, 0);
   
  //画一个大的圆形
  UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, ovalWH, ovalWH)];
   
  [[UIColor orangeColor]set];
   
  [path fill];
   
  //设置裁剪区域
  UIBezierPath *path1 = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(border, border, imageWH, imageWH)];
  [path1 addClip];
   
  //绘制图片
  [image drawAtPoint:CGPointMake(border, border)];
   
  //从上下文中获取图片
  _imageView.image = UIGraphicsGetImageFromCurrentImageContext();
   
  //关闭上下文
  UIGraphicsEndImageContext();
   
}

- (void)viewDidLoad {
  [super viewDidLoad];
   
  //开启上下文
  UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, 0);
   
  //获取上下文
  CGContextRef ctx = UIGraphicsGetCurrentContext();
   
  //把控件上的图层渲染到上下文
  [self.view.layer renderInContext:ctx];
   
  //获取上下文中的图片
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
   
  //关闭上下文
  UIGraphicsEndImageContext();
   
  //保存图片到相册
  UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
   
}