回调强引用循环答案

【问题标题】：Callback strong Reference Cycle回调强引用循环
【发布时间】：2018-04-27 01:33:18
【问题描述】：

以下是否创建了一个强引用循环？我有一种感觉是因为我在回调中引用了self。

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    [picker dismissViewControllerAnimated:YES completion:^{
        UIImage *image = [self cropImageWithInfo:info];
        if (currentScreen == CurrentScreenApartment) {
            [self.profileViewModel.apartmentPhotos addObject:[RuntimePhoto runtimePhotoWithImage:image]];
        }
        else {
            [self.profileViewModel.userPhotos addObject:[RuntimePhoto runtimePhotoWithImage:image]];
        }
        dispatch_async(dispatch_get_main_queue(), ^{
            [self reloadPhotosCell];
        });
    }];
}

【问题讨论】：

标签： objective-c asynchronous reference-cycle

【解决方案1】：

你可以使用 self 的弱变量：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

    typeof(self) __weak weakSelf = self;

    [picker dismissViewControllerAnimated:YES completion:^{
        UIImage *image = [weakSelf cropImageWithInfo:info];
        if (currentScreen == CurrentScreenApartment) {
            [weakSelf.profileViewModel.apartmentPhotos addObject:[RuntimePhoto runtimePhotoWithImage:image]];
        }
        else {
            [weakSelf.profileViewModel.userPhotos addObject:[RuntimePhoto runtimePhotoWithImage:image]];
        }
        dispatch_async(dispatch_get_main_queue(), ^{
            [weakSelf reloadPhotosCell];
        });
    }];
}

【讨论】：