iOS－－二维码生成和扫描

二维码扫描iOS端，网上已经有很大量的代码了，感谢各位大神们的分享，现在自己简单对此做一点纪录，便于以后查看。

本文源代码已放置GitHub上，地址为：https://github.com/gaussli/QRCodeDemo

由于Demo涉及到摄像头操作，所以最好能使用真机测试。

部分解释：

1. 通过摄像头扫描二维码需要导入系统库AVFoundation.framework

2. 通过调用2个函数，就能按照给定的字符串生成一张UIImage类型的图片，这两个函数分别为createNonInterpolatedUIImageFormCIImage和imageBlackToTransparent。

3. 扫描二维码过程，跳转到ScanQRCodeViewController类型的ViewController对象，实现一个回调代理ScanQRCodeDelegate中的qrCodeFinishWithMessage函数，即可获取得扫描成功后的二维码包含的字符串。

使用过程：

1. 如果需要扫描二维码操作，导入系统库AVFoundation.framework；

2. 导入Demo中的文件，ScanQRCodeViewController.h、ScanQRCodeViewController.m和MacroDefinition.h（定义一些常量，不导入可自己写）

3. 生成二维码：

1）复制黏贴生成二维码的四个必要函数，分别为createNonInterpolatedUIImageFormCIImage、createQRForString、ProviderReleaseData和imageBlackToTransparent

#pragma mark - 生成二维码逻辑#pragma mark InterpolatedUIImage- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size {    CGRect extent = CGRectIntegral(image.extent);    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));    // create a bitmap image that we'll draw into a bitmap context at the desired size;    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);    // Create an image with the contents of our bitmap    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);    // Cleanup    CGContextRelease(bitmapRef);    CGImageRelease(bitmapImage);    return [UIImage imageWithCGImage:scaledImage];}#pragma mark QRCodeGenerator- (CIImage *)createQRForString:(NSString *)qrString {    // Need to convert the string to a UTF-8 encoded NSData object    NSData *stringData = [qrString dataUsingEncoding:NSUTF8StringEncoding];    // Create the filter    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];    // Set the message content and error-correction level    [qrFilter setValue:stringData forKey:@"inputMessage"];    [qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"];    // Send the image back    return qrFilter.outputImage;}#pragma mark imageToTransparentvoid ProviderReleaseData (void *info, const void *data, size_t size){    free((void*)data);}- (UIImage*)imageBlackToTransparent:(UIImage*)image withRed:(CGFloat)red andGreen:(CGFloat)green andBlue:(CGFloat)blue{    const int imageWidth = image.size.width;    const int imageHeight = image.size.height;    size_t      bytesPerRow = imageWidth * 4;    uint32_t* rgbImageBuf = (uint32_t*)malloc(bytesPerRow * imageHeight);    // create context    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();    CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace,                                                 kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);    CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), image.CGImage);    // traverse pixe    int pixelNum = imageWidth * imageHeight;    uint32_t* pCurPtr = rgbImageBuf;    for (int i = 0; i < pixelNum; i++, pCurPtr++){        if ((*pCurPtr & 0xFFFFFF00) < 0x99999900){            // change color            uint8_t* ptr = (uint8_t*)pCurPtr;            ptr[3] = red; //0~255            ptr[2] = green;            ptr[1] = blue;        }else{            uint8_t* ptr = (uint8_t*)pCurPtr;            ptr[0] = 0;        }    }    // context to image    CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, ProviderReleaseData);    CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8, 32, bytesPerRow, colorSpace,                                        kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider,                                        NULL, true, kCGRenderingIntentDefault);    CGDataProviderRelease(dataProvider);    UIImage* resultUIImage = [UIImage imageWithCGImage:imageRef];    // release    CGImageRelease(imageRef);    CGContextRelease(context);    CGColorSpaceRelease(colorSpace);    return resultUIImage;}

2）声明UIImage对象，调用上述第二个解释中两个函数

    // 设置二维码ImageView    _qrcodeImageView = [[UIImageView alloc] initWithFrame:CGRectMake((JH_DEVICE_WIDTH-100)/2.0, JH_STATUSBAR_HEIGHT*2.0, 100, 100)];    UIImage *qrcode = [self createNonInterpolatedUIImageFormCIImage:[self createQRForString:@"QRCode Test"] withSize:100];    UIImage *customQrcode = [self imageBlackToTransparent:qrcode withRed:60.0f andGreen:74.0f andBlue:89.0f];    _qrcodeImageView.image = customQrcode;    [self.view addSubview:_qrcodeImageView];

4. 扫描二维码：

1）实现二维码扫描完成代理ScanQRCodeDelegate

2）新建扫描ViewController并进行跳转

    ScanQRCodeViewController *scanQRCodeViewController = [[ScanQRCodeViewController alloc] init];    scanQRCodeViewController.delegate = self;    [self presentViewController:scanQRCodeViewController animated:YES completion:^{        ;    }];

3）实现回调代理函数qrCodeFinishWithMessage，我这里只是简单的把扫描结果赋值给UILabel对象

#pragma mark - 自定义代理实现#pragma mark ScanQRCodeDelegate扫描完成代理- (void) qrCodeFinishWithMessage:(NSString *)message {    _scanResultLabel.text = message;}