//將生成的鏈接放置到圖片
self.codeImageV.image=[self createNonInterpolatedUIImageFormCIImage:[self creatQRcodeWithUrlstring:@"您要生成鏈接"] withSize:150];

- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size
{
    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    
    // 1.創建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);
    return [UIImage imageWithCGImage:scaledImage];
}

- (CIImage *)creatQRcodeWithUrlstring:(NSString *)urlString{
    
    // 1.實例化二維碼濾鏡
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    // 2.恢復濾鏡的默認屬性 (因為濾鏡有可能保存上一次的屬性)
    [filter setDefaults];
    // 3.將字符串轉換成NSdata
    NSData *data  = [urlString dataUsingEncoding:NSUTF8StringEncoding];
    // 4.通過KVO設置濾鏡, 傳入data, 將來濾鏡就知道要通過傳入的數據生成二維碼
    [filter setValue:data forKey:@"inputMessage"];
    // 5.生成二維碼
    CIImage *outputImage = [filter outputImage];
    return outputImage;
}