weakSelf+strongSelf

本文深入探讨了Objective-C中弱引用(__weak)与强引用(__strong)的使用场景与作用。通过具体示例解释了在block外使用__weak typeof(self) weakSelf = self;的作用是对象释放时自动对weak指针置nil,防止循环引用。而在block内使用__strong typeof(weakSelf) strongSelf = weakSelf;则保证了self在block执行过程中始终存在。

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 block外:__weak __typeof(self)weakSelf = self;

作用:对象释放时,自动对weak指针置nil,self不知道什么时候释放;

block内:__strong __typeof(weakSelf) strongSelf = weakSelf;

作用:保证self在block执行过程中,一直存在;

 

 

处理下面代码可能出现线程问题的情况- (void)shutterCamera { AVCaptureConnection *videoConnection = [self.ImageOutPut connectionWithMediaType:AVMediaTypeVideo]; UIDeviceOrientation curDeviceOrientation = [[UIDevice currentDevice] orientation]; if (!videoConnection || !self.session.isRunning) { ATLog(@"take photo failed!"); return; } AVCaptureVideoOrientation avcaptureOrientation = [self avOrientationForDeviceOrientation:curDeviceOrientation]; [videoConnection setVideoOrientation:avcaptureOrientation]; [videoConnection setVideoScaleAndCropFactor:self.effectiveScale]; MJWeakSelf; [self.ImageOutPut captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) { dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ __strong typeof(weakSelf) strongSelf = weakSelf; if (!strongSelf) return; if (imageDataSampleBuffer) { NSData * imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer]; strongSelf.image = [UIImage imageWithData:imageData]; if (strongSelf.image) { strongSelf.image = [UIImage updateImageSize:strongSelf.image]; } strongSelf.image = [[TZImageManager manager] fixOrientation:strongSelf.image];//[UIImage fixOrientation:weakSelf.image]; PHAuthorizationStatus authorStatus = [PHPhotoLibrary authorizationStatus]; if (authorStatus == PHAuthorizationStatusAuthorized) { [[TZImageManager manager] savePhotoWithImage:strongSelf.image completion:^(PHAsset *asset, NSError *error) { [strongSelf addPHAsset:asset]; }]; }else{ [strongSelf gotoEditImageController:strongSelf.image asset:nil]; } } }); }]; } - (void)gotoEditImageController:(UIImage *)image asset:(PHAsset *)asset { if (!image) { [ATMBPHud showErrorToView:self.view text:@"获取图片失败,请重新再试"]; return; } if (image) { image = [UIImage updateImageSize:image]; } YasicClipPage *vc = [[YasicClipPage alloc] init]; vc.userId = self.userId; vc.attention = self.attention; vc.targetImage = image; vc.searchType = self.searchType; vc.asset = asset; // [self stopSession]; dispatch_async(dispatch_get_main_queue(), ^{ [[KDUserInterfaceTool currenrtopViewController].navigationController pushViewController:vc animated:YES]; [self removeViewController:self]; }); } - (void)addPHAsset:(PHAsset *)asset { MJWeakSelf; TZAssetModel *assetModel = [[TZImageManager manager] createModelWithAsset:asset]; [ATHUD show]; [[TZImageManager manager] requestImageDataForAsset:assetModel.asset completion:^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) { [ATHUD dismiss]; UIImage *image = [UIImage imageWithData:imageData];//[[TZImageManager manager] fixOrientation:[UIImage imageWithData:imageData]]; image = [[TZImageManager manager] fixOrientation:image]; [weakSelf gotoEditImageController:image asset:asset]; } progressHandler:^(double progress, NSError *error, BOOL *stop, NSDictionary *info) { ATLog(@"%f",progress); }]; } #pragma --mark 获取大图 - (void)getImageWithModel:(TZAssetModel *)model { if (model == nil) { ATLog(@"图片为空"); return; } [ATHUD show]; WS(weakSelf) [[TZImageManager manager] requestImageDataForAsset:model.asset completion:^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) { [ATHUD dismiss]; UIImage *image = [UIImage imageWithData:imageData]; if (weakSelf.downBtnClick) { weakSelf.downBtnClick(image, model); } } progressHandler:^(double progress, NSError *error, BOOL *stop, NSDictionary *info) { ATLog(@"%f",progress); }]; }
07-25
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