给UIImage添加背景颜色

最近开发功能涉及到生成二维码，但是生成的二维码是黑色透明底的，分享到微信好友之后点击会看不到，所以需要给二维码背景修改为白色，实现方法如下:

//设置图片的背景颜色

- (UIImage *)colorizeImage:(UIImage *)baseImage withBackgroundColor:(UIColor *)theColor {

UIGraphicsBeginImageContext(baseImage.size);

CGContextRef ctx = UIGraphicsGetCurrentContext();

CGRect area = CGRectMake(0, 0, baseImage.size.width, baseImage.size.height);

CGContextScaleCTM(ctx, 1, -1);

CGContextTranslateCTM(ctx, 0, -area.size.height);

​CGContextSaveGState(ctx);

​[theColor set];

CGContextFillRect(ctx, area);

 CGContextRestoreGState(ctx);

CGContextSetBlendMode(ctx, kCGBlendModeMultiply);

CGContextDrawImage(ctx, area, baseImage.CGImage); //改变背景

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

 return newImage;

}

​