@interface UIImage (Resize)

//按形状切割图像

• (UIImage*)cutImageWithRadius:(int)radius;

@end
//图片剪切

• (UIImage*)cutImageWithRadius:(int)radius
  {
  UIGraphicsBeginImageContext(self.size);
  CGContextRef gc = UIGraphicsGetCurrentContext();

  float x1 = 0.;
  float y1 = 0.;
  float x2 = x1+self.size.width;
  float y2 = y1;
  float x3 = x2;
  float y3 = y1+self.size.height;
  float x4 = x1;
  float y4 = y3;
  radius = radius*2;

  CGContextMoveToPoint(gc, x1, y1+radius);
  CGContextAddArcToPoint(gc, x1, y1, x1+radius, y1, radius);
  CGContextAddArcToPoint(gc, x2, y2, x2, y2+radius, radius);
  CGContextAddArcToPoint(gc, x3, y3, x3-radius, y3, radius);
  CGContextAddArcToPoint(gc, x4, y4, x4, y4-radius, radius);

  CGContextClosePath(gc);
  CGContextClip(gc);

  CGContextTranslateCTM(gc, 0, self.size.height);
  CGContextScaleCTM(gc, 1, -1);
  CGContextDrawImage(gc, CGRectMake(0, 0, self.size.width, self.size.height), self.CGImage);

  UIImage *newimage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();

  return newimage;
  }