// image 分类

- (UIImage *)circleImage{

// NO 代表透明

UIGraphicsBeginImageContextWithOptions(self.size, NO, 1);

// 获得上下文

CGContextRef ctx = UIGraphicsGetCurrentContext();

// 添加一个圆

CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);

// 方形变圆形

CGContextAddEllipseInRect(ctx, rect);

// 裁剪

CGContextClip(ctx);

// 将图片画上去

[self drawInRect:rect];

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

return image;

}