为什么 AFNetWork 在 URLSession:dataTask:didReceiveResponse:completionHandler 中崩溃

Question

我的应用程序在 AFURLSessionManager.m 的 URLSession:dataTask:didReceiveResponse:completionHandler 中的第 4 行崩溃，似乎 self 对象被释放，Func 是我们添加回调的地方：

- (void) Func:(AFHTTPSessionManager *)sessionManager {
    @weakify(self);
    [sessionManager setDataTaskDidReceiveResponseBlock:^NSURLSessionResponseDisposition(NSURLSession * _Nonnull session,                                                               NSURLSessionDataTask * _Nonnull dataTask, NSURLResponse * _Nonnull response) {
        @strongify(self);
        if (!self) {
            return NSURLSessionResponseCancel;
        }
      ......
     }
  ......
}

     - (void)URLSession:(NSURLSession *)session
              dataTask:(NSURLSessionDataTask *)dataTask
    didReceiveResponse:(NSURLResponse *)response
     completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler
    {
1        NSURLSessionResponseDisposition disposition = NSURLSessionResponseAllow;
2   
3       if (self.dataTaskDidReceiveResponse) {
4           disposition = self.dataTaskDidReceiveResponse(session, dataTask, response);(line 1115 of original m file)
5       }
6   
7   }

崩溃堆栈：

    Exception Type: SIGSEGV
    Exception Codes: SEGV_ACCERR at 0x58fe10485d20
    Thread 13 Crashed:
    0 libobjc.A.dylib 0x000000019d5f9c20 objc_msgSend
    1 APPInfo 0x0000000105204e0c -[AFURLSessionManager URLSession:dataTask:didReceiveResponse:completionHandler:] at AFURLSessionManager.m:1115:28
    2 CFNetwork 0x00000001a54c9934 CFURLConnectionCreateWithProperties
    3 Foundation 0x19e75f2f0 __NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__
    4 Foundation 0x19e7334a0 -[NSBlockOperation main]
    5 Foundation 0x19e733430 __NSOPERATION_IS_INVOKING_MAIN__
    6 Foundation 0x19e6f47d8 -[NSOperation start]
    7 Foundation 0x19e6f450c __NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__
    8 Foundation 0x19e6f9c20 __NSOQSchedule_f
    9 libdispatch.dylib 0x1ab8c1114 _dispatch_block_async_invoke2
    10 libdispatch.dylib 0x1ab8b1fdc _dispatch_client_callout
    11 libdispatch.dylib 0x1ab8b546c _dispatch_continuation_pop
    12 libdispatch.dylib 0x1ab8b4ad4 _dispatch_async_redirect_invoke
    13 libdispatch.dylib 0x1ab8c3a6c _dispatch_root_queue_drain
    14 libdispatch.dylib 0x1ab8c4284 _dispatch_worker_thread2
    15 libsystem_pthread.dylib 0x1f133bdbc _pthread_wqthread
    16 libsystem_pthread.dylib 0x1f133bb98 start_wqthread

Answer 1

很可能是在调用完成处理程序时释放对象。要确定，需要更多代码片段。

您应该在完成处理程序的开头检查

self

是否为

nil

。 或者您应该确保对该实例的引用被强烈保留，因此在调用完成处理程序之前它不会被释放。

确保在完成处理程序启动之前引用是弱的，然后在执行时保持强引用的一种模式是：

__weak typeof(self) weakSelf = self;
[someObj someCall:^{
    __strong typeof(self) strongSelf = weakSelf;
    if (strongSelf == nil) return;
    ...
}];

希望这有帮助。