给图片添加文字水印

- (UIImage *) addTextToImage:(UIImage *) baseImage text:(NSString *)text atRect:(CGRect) rect{

int w = baseImage.size.width;

int h = baseImage.size.height;

UIGraphicsBeginImageContext(baseImage.size);

[[UIColor redColor] set];

[baseImage drawInRect:CGRectMake(0, 0, w, h)];

[text drawInRect:rect withFont:[UIFont systemFontOfSize:20]];

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return image;

}