基础功能，具体细节处理，需要再添加；

授权

二维码扫描需要拍照功能，

    AVAuthorizationStatus authorizationStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
    switch (authorizationStatus) {
        case AVAuthorizationStatusNotDetermined: {
            [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler: ^(BOOL granted) {
                if (granted) {
                    [self startCapture];
                } else {
                    NSLog(@"%@", @"访问受限");
                }
            }];
            break;
        }
        case AVAuthorizationStatusAuthorized: {
            [self startCapture];
            break;
        }
        case AVAuthorizationStatusRestricted:
        case AVAuthorizationStatusDenied: {
            NSLog(@"%@", @"访问受限");
            break;
        }
        default: {
            break;
        }
    }

开启拍照扫描

- (void)startCapture {
    dispatch_async(dispatch_get_main_queue(), ^{
        AVCaptureSession *session = [[AVCaptureSession alloc] init];
        AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
        NSError *error;
        AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
        if (deviceInput) {
            [session addInput:deviceInput];
            
            AVCaptureMetadataOutput *metadataOutput = [[AVCaptureMetadataOutput alloc] init];
            [metadataOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
            [session addOutput:metadataOutput]; // 这行代码要在设置 metadataObjectTypes 前
            metadataOutput.metadataObjectTypes = @[AVMetadataObjectTypeQRCode];
            
            AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
            previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
            previewLayer.frame = self.view.frame;
            [self.view.layer insertSublayer:previewLayer atIndex:0];
            
            
            CGRect rect = CGRectMake(CZScanLeftAndRightPadding, CZScanTopPadding, CGRectGetWidth([UIScreen mainScreen].bounds) - 2 * CZScanLeftAndRightPadding, CGRectGetWidth([UIScreen mainScreen].bounds) - 2 * CZScanLeftAndRightPadding);
            
            [[NSNotificationCenter defaultCenter] addObserverForName:AVCaptureInputPortFormatDescriptionDidChangeNotification
                                                              object:nil
                                                               queue:[NSOperationQueue currentQueue]
                                                          usingBlock: ^(NSNotification *_Nonnull note) {
                                                              
                                                              metadataOutput.rectOfInterest = [previewLayer metadataOutputRectOfInterestForRect:rect]; // 如果不设置，整个屏幕都可以扫
                                                          }];
            
            QRScanView *scanView = [[QRScanView alloc] initWithScanRect:rect];
            [self.view addSubview:scanView];
            
            [session startRunning];
            self.messageLabel.hidden = YES;
        } else {
            NSLog(@"%@", error);
        }
    });
}

扫描成果

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection {
    AVMetadataMachineReadableCodeObject *metadataObject = metadataObjects.firstObject;
    if ([metadataObject.type isEqualToString:AVMetadataObjectTypeQRCode]) { // 成功后系统不会停止扫描，可以用一个变量来控制。
        if (self.scanComplete) {
            self.scanComplete(metadataObject.stringValue);
        }
        
        NSLog(@"提示扫描成功没，1秒后返回，不然刷就回去了");
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            [self.navigationController popViewControllerAnimated:YES];
        });
    }
}

iOS8 识别图中二维码

给 image 加个 类别就可以用了

- (NSString *)scanQRCodeFromImage {
    
    CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{ CIDetectorAccuracy:CIDetectorAccuracyHigh }];
    CIImage *image = [[CIImage alloc] initWithImage:self];
    NSArray *features = [detector featuresInImage:image];
    CIQRCodeFeature *feature = [features firstObject];
    
    if (feature) {
        return feature.messageString;
    } else {
        return @"没有二维码";
    }
}

生成二维码

同样 拓展类就行了，可能生成的图片比较糊，那么就放大倍数大一点就好了；

+ (UIImage *)createQRImageWithContent:(NSString *)content scale:(CGFloat)scale {
    
    NSData *data = [content dataUsingEncoding:NSUTF8StringEncoding]; // NSISOLatin1StringEncoding 编码

    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [filter setValue:data forKey:@"inputMessage"];
    [filter setValue:@"M" forKey:@"inputCorrectionLevel"];// L: 7% M: 15% Q: 25% H: 30%
    
    CIImage *outputImage = filter.outputImage;

    CGAffineTransform transform = CGAffineTransformMakeScale(scale, scale); // scale 为放大倍数
    CIImage *transformImage = [outputImage imageByApplyingTransform:transform];

    // 保存
    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef imageRef = [context createCGImage:transformImage fromRect:transformImage.extent];
    UIImage *qrCodeImage = [UIImage imageWithCGImage:imageRef];
    
    CGImageRelease(imageRef);
    
    return qrCodeImage;
}

https://github.com/JuYiWei/CZ_Demos
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