關(guān)于二維碼生成，網(wǎng)上也是有很多，三方庫也是有的如zxing，也是挺好用，這里介紹的是通過CIFilter創(chuàng)建二維碼

iOS7之后，可以使用原生的CIFilter創(chuàng)建二維碼，下面是相應(yīng)的代碼
首先是二維碼的生成，使用CIFilter很簡單，直接傳入生成二維碼的字符串即可：

 - (CIImage *)createQRForString:(NSString *)qrString {
    NSData *stringData = [qrString dataUsingEncoding:NSUTF8StringEncoding];
    // 創(chuàng)建filter
    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    // 設(shè)置內(nèi)容和糾錯級別
    [qrFilter setValue:stringData forKey:@"inputMessage"];
    [qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"];
    // 返回CIImage
    return qrFilter.outputImage;
}

因?yàn)樯傻亩S碼是一個CIImage，我們直接轉(zhuǎn)換成UIImage的話大小不好控制，所以使用下面方法返回需要大小的UIImage：
下面同事添加了水印

 - (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size {
    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
   // 1.創(chuàng)建bitmap;
    size_t width = CGRectGetWidth(extent) * scale;
    size_t height = CGRectGetHeight(extent) * scale;
    
    CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
    CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
    CIContext *context = [CIContext contextWithOptions:nil];
    
    CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
    CGContextScaleCTM(bitmapRef, scale, scale);
    CGContextDrawImage(bitmapRef, extent, bitmapImage);
    
    // 2.保存bitmap到圖片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef); 
    CGImageRelease(bitmapImage);
    
    //原圖
    UIImage *outputImage = [UIImage imageWithCGImage:scaledImage];

    UIGraphicsBeginImageContextWithOptions(outputImage.size, NO, [[UIScreen mainScreen] scale]);
    [outputImage drawInRect:CGRectMake(0,0 , size, size)];
    //水印圖
    UIImage *waterimage = [UIImage imageNamed:@"icon"];
    [waterimage drawInRect:CGRectMake((size-waterImagesize)/2.0, (size-waterImagesize)/2.0, waterImagesize, waterImagesize)];
    UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newPic;

}

以上是代碼的一些匯總，希望能幫到大家，共同努力！

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