实现一个原声的扫描识别二维码的功能

二维码扫描识别的有名的第三方库有zbar,zxing,ios7以后iOS自带的AVFoundation框架可以实现二维码扫描识别的功能

扫码

    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (!input) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"error" message:error.localizedDescription delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        [alert show];
        [self.navigationController popViewControllerAnimated:YES];
    }
    AVCaptureSession* session = [[AVCaptureSession alloc] init];
    [session addInput:input];
    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
    [output setMetadataObjectsDelegate:self queue:dispatch_queue_create("capture_queue", NULL)];
    [session addOutput:output];
    output.metadataObjectTypes = @[AVMetadataObjectTypeQRCode];
    
    [[NSNotificationCenter defaultCenter] addObserverForName:AVCaptureInputPortFormatDescriptionDidChangeNotification object:nil queue:[NSOperationQueue currentQueue] usingBlock:^(NSNotification * _Nonnull note) {
        output.rectOfInterest =[_previewLayer metadataOutputRectOfInterestForRect:scanRect];
    }];

识别二维码

- (void)scanImageQRCode:(NSDictionary*)info{
UIImage *image = [info objectForKey:UIImagePickerControllerEditedImage];
if (!image) {
    image = [info objectForKey:UIImagePickerControllerOriginalImage];
}
CIQRCodeFeature *feature = (CIQRCodeFeature*)[[self.detector featuresInImage:[CIImage imageWithCGImage:image.CGImage]] firstObject];
if (feature) {
    UIAlertView  *alert = [[UIAlertView alloc] initWithTitle:@"Tip" message:feature.messageString delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
    [alert show];
}else{
    UIAlertView  *alert = [[UIAlertView alloc] initWithTitle:@"Tip" message:@"无法识别二维码" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
    [alert show];
}
[self startScan];
}

生成二维码

NSData *data = [QRCodeText dataUsingEncoding:NSUTF8StringEncoding];
        CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
        [filter setValue:data forKey:@"inputMessage"];
        CIImage *ciImage = filter.outputImage;
        CGFloat scale = CGRectGetWidth(self.QRCodeImage.bounds)/CGRectGetWidth(ciImage.extent);
        CIImage *transformImage = [ciImage imageByApplyingTransform:CGAffineTransformMakeScale(scale ,scale)];
        self.QRCodeImage.image = [[UIImage imageWithCIImage:transformImage] resizableImageWithCapInsets:UIEdgeInsetsMake(20, 20, 20, 20)];
        UIImageWriteToSavedPhotosAlbum(self.QRCodeImage.image, self, nil, NULL);

demo地址
参考：http://c0ming.me/qr-code-scan/