iOS關(guān)于ZXing掃碼在控制器dissmiss導(dǎo)致崩潰的問題

最近因?yàn)轫?xiàng)目中有掃碼登錄的需求先馆，一開始用的是系統(tǒng)的AVFoundation庫實(shí)現(xiàn)的掃碼功能

@property (nonatomic,strong) AVCaptureSession *captureSession;//捕捉會話

@property (nonatomic,strong) AVCaptureDeviceInput *deviceInput;//輸入流

@property (nonatomic,strong) AVCaptureMetadataOutput *metaDataOutput;//輸出流

@property (nonatomic,strong) AVCaptureVideoPreviewLayer *videoPreviewLayer;//預(yù)覽圖層

//開始掃描
- (void)startCapture{
    if (![self requestDeviceAuthorization]) {
        [[UUCommon shareInstance] uu_alertWithTitle:@"沒有相機(jī)訪問權(quán)限" message:@"請?jiān)谠O(shè)置->通用->相機(jī)中允許訪問" centerStr:@"去設(shè)置" centerItem:^{
            NSURL *url = [[NSURL alloc] initWithString:UIApplicationOpenSettingsURLString];// 跳轉(zhuǎn)至系統(tǒng)設(shè)置
            [[UIApplication sharedApplication] openURL:url];
        }];
        return;
    }
    
    [self.captureSession beginConfiguration];
    if ([self.captureSession canAddInput:self.deviceInput]) {
        [self.captureSession addInput:self.deviceInput];
    }
    // 設(shè)置數(shù)據(jù)輸出類型温亲，需要將數(shù)據(jù)輸出添加到會話后，才能指定元數(shù)據(jù)類型端考，否則會報(bào)錯(cuò)
    if ([self.captureSession canAddOutput:self.metaDataOutput]) {
        [self.captureSession addOutput:self.metaDataOutput];
        //設(shè)置掃碼支持的編碼格式(如下設(shè)置條形碼和二維碼兼容)
        NSArray *types = @[AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode128Code,AVMetadataObjectTypeCode93Code];
        self.metaDataOutput.metadataObjectTypes =types;
    }
    [self.captureSession commitConfiguration];
    [self.captureSession startRunning];
}

//停止掃描
- (void)stopCapture{
    [self.captureSession stopRunning];
    [self.shadowView uu_scanStop];
}

#pragma mark - 請求權(quán)限
- (BOOL)requestDeviceAuthorization{
    
    AVAuthorizationStatus deviceStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
    if (deviceStatus == AVAuthorizationStatusRestricted ||
        deviceStatus ==AVAuthorizationStatusDenied){
        return NO;
    }
    return YES;
}

#pragma mark - AVCaptureMetadataOutputObjectsDelegate
- (void)captureOutput:(AVCaptureOutput *)output didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
    //獲取到掃描的數(shù)據(jù)
    AVMetadataMachineReadableCodeObject *dateObject = (AVMetadataMachineReadableCodeObject *) [metadataObjects lastObject];
    [self.captureSession stopRunning];
    NSLog("%@", dateObject.stringValue);
}

后來參考一下第三方的ZXing庫紫新，可以解決系統(tǒng)掃碼識別亂碼問題，主要是和安卓端保持一致担平，就開始修改成ZXing的掃碼：

//導(dǎo)入頭文件
#import <ZXingObjC/ZXingObjC.h>
//遵循代理<ZXCaptureDelegate>
//ZXCapture捕獲器
@property (nonatomic, strong) ZXCapture *capture;             //ZXCapture捕獲器

//加載ZXCapture捕獲器
- (void)setupCapture {
self.capture = [[ZXCapture alloc] init];
    self.capture.camera = self.capture.back;
    //自動聚焦
    self.capture.focusMode = AVCaptureFocusModeContinuousAutoFocus;
    [self.view.layer addSublayer:self.capture.layer];
    self.capture.delegate = self;
}

//開始掃描
- (void)startCapture {
    if (![self requestDeviceAuthorization]) {
        [self alertWithTitle:@"沒有相機(jī)權(quán)限" message:@"請?jiān)谠O(shè)置-通用-相機(jī)-允許訪問" leftStr:@"去設(shè)置" rightStr:@"取消" leftItem:^{
            NSURL *openURL = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
            [[UIApplication sharedApplication] openURL:openURL];
        } rightItem:^{
            
        }];
        
        return;
    }
    
    //TODO:ZXing捕獲器
    [self.capture start];
}

//停止掃描
- (void)stopCapture {
    //TODO:ZXing停止掃碼
    [self.capture stop];
}

#pragma mark - ZXCaptureDelegate
- (void)captureResult:(ZXCapture *)capture result:(ZXResult *)result {
    if (!result) return;
    
    if (self.capture.layer.superlayer) {
        if (result.barcodeFormat == kBarcodeFormatQRCode) {
            AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
            
            [self stopCapture];
            
            NSLog(@"識別的二維碼的內(nèi)容 = %@", result.text);
        }
    }
}

這就完了示绊？等等，掃碼的功能是實(shí)現(xiàn)了暂论，本例中用到的是模態(tài)出的掃描二維碼頁面面褐，dismiss的時(shí)候在iOS13的機(jī)型上會閃退。通過百度大法后才知道ZXing庫需要在控制器dismiss的前移除layer取胎，不然會導(dǎo)致崩潰展哭。

修復(fù)的代碼：
self.capture.delegate = nil;
[self.capture.layer removeFromSuperlayer];

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