iOS二维码扫描获取文字信息。

1 需要工程plist文件设置开启摄像机（扫描用到），相册权限（从照片获取二维码用到）
2 摄像机扫描代码如下，直接在viewdidload就可调用，查看效果，
-(void)configUI{
    //获取设备
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    //输入流
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
    
    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
    
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    
    output.rectOfInterest = CGRectMake(0.05, 0.2, 0.7, 0.6);
    
    self.session = [[AVCaptureSession alloc] init];
    
    [self.session setSessionPreset:AVCaptureSessionPresetHigh];
    
    [self.session addInput:input];
    
    [self.session addOutput:output];
    
    output.metadataObjectTypes = @[AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN13Code,AVMetadataObjectTypeEAN8Code,AVMetadataObjectTypeCode128Code];
    
    self.prelayer = [AVCaptureVideoPreviewLayer layerWithSession:_session];
    _prelayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    _prelayer.frame = self.view.layer.bounds;
    
    [self.view.layer insertSublayer:self.prelayer atIndex:0];
    
    [self.session startRunning];
    

}
//当然，获取到信息，输出二维码信息的代理方法为:
-(void)captureOutput:(AVCaptureOutput *)output didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
    
    AVMetadataMachineReadableCodeObject *obj = metadataObjects[0];
    NSLog(@"object:%@",metadataObjects);
//    NSLog(@"object:%@",[obj stringValue]);
    [self.session stopRunning];
}

3 以上是直接摄像机扫描，以下是从相册获取照片扫描的处理（这里只贴取从相机获取到图片之后的操作）
//从相册识别二维码并进行跳转
-(void)scanCodeFromAlbum:(UIImage*)img{
    //cidetector可用于人脸识别等.
    CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{CIDetectorAccuracy:CIDetectorAccuracyHigh}];
    
    //取得识别结果
    NSArray *features = [detector featuresInImage:[CIImage imageWithCGImage:img.CGImage]];
    for (int index = 0 ; index<features.count; index++) {
        CIQRCodeFeature *feature = [features objectAtIndex:index];
        NSString *result = feature.messageString;
        NSLog(@"result:%@",result);
    }
}

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