苹果原生二维码在iOS7上的那些坑

1.iOS7上 每一个AVCaptureSession只能 startRunning一次有效,如果扫出一次结果之后，照相机界面会停在最后的音相界面.再次调用startRunning无效.只能重新创建AVCaptureSession.

2.iOS7上扫一次码，会触发无数次delegate方法.只能做判断.

下面是相关代码:

- (id)initWithView:(UIView *)_viewLayer finishBlock:(void(^)(NSArray *metadataObjects,BOOL success))block {

    if (self = [super init]) {

        self.superView = _viewLayer;

        self.finishBlock = block;

//        [self setupCamera];

    }

    return self;

}

- (void)dealloc {

    [_session stopRunning];

}

- (void)setupCamera

{

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        isReading = YES;

        // 耗时的操作

        // Device

        _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

        

        // Input

        _input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];

        

        // Output

        _output = [[AVCaptureMetadataOutput alloc]init];

        [_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];

        

        // Session

        _session = [[AVCaptureSession alloc]init];

        [_session setSessionPreset:AVCaptureSessionPresetHigh];

        if ([_session canAddInput:self.input])

        {

            [_session addInput:self.input];

        }

        

        if ([_session canAddOutput:self.output])

        {

            [_session addOutput:self.output];

        }

        // 条码类型 AVMetadataObjectTypeQRCode

        _output.metadataObjectTypes =@[AVMetadataObjectTypeQRCode];

        dispatch_async(dispatch_get_main_queue(), ^{

            // 更新界面

            // Preview

            _preview =[AVCaptureVideoPreviewLayer layerWithSession:self.session];

            _preview.videoGravity = AVLayerVideoGravityResizeAspectFill;

            _preview.frame = self.superView.bounds;

            [self.superView.layer insertSublayer:self.preview atIndex:0];

            // Start

            [_session startRunning];

        });

    });

}

- (void)startScaning {

    if (!_session) {//坑爹的iOS7startRunning只能有效一次

        [self setupCamera];

    }

}

- (void)stopScaning {//坑爹的iOS7startRunning只能有效一次，只能全部重置为nil在重新生成

    [self.session stopRunning];

    [self.preview removeFromSuperlayer];

    self.session = nil;

    self.preview = nil;

    self.device = nil;

    self.input = nil;

    self.output = nil;

}

#pragma mark AVCaptureMetadataOutputObjectsDelegate

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection

{

    if (!isReading) {//坑爹的iOS7扫一次二维码会不停的触发代理方法

        return;

    }

    if ([metadataObjects count] >0)

    {

        if (self.finishBlock) {

            self.finishBlock(metadataObjects,YES);

        }

        isReading = NO;

    }

}