当可达性改变时,MKNetworkKit操作不会恢复/完成

Question

我是新手MKNetworkKit,但我已经能够将它添加到我的项目中,除非处理可达性更改,否则它完全正常工作.

情况如下:

1. 我禁用WiFi并运行应用程序.
2. 即使没有可达性,我POST也通过创建一个MKNetworkOperationfrom我的MKNetworkEngine子类来请求(使用)一些数据.在请求数据之前,操作被设置为freezable(根据Mugunth Kumar的文档).
3. 在启用WiFi后,调用checkAndRestoreFrozenOperationsin MKNetworkEngine并且它检测到有一个挂起的操作(创建的没有可达性),它尝试入队.
4. 之后,我的onCompletion块永远不会被调用.

有什么我不明白冻结操作+可达性MKNetworkKit吗？冻结是否仅适用于请求开始后可达性发生变化的操作？或者我应该实现自己的可达性更改块？

这是我的MKNetworkEngine子类中的代码,它创建操作并启动请求.请注意,不相关的代码已被禁止.

NSMutableDictionary *params = [NSMutableDictionary dictionaryWithObject:@"value" forKey:@"param"];
MKNetworkOperation *op = [self operationWithPath:MYPATH
                                          params:params
                                      httpMethod:@"POST"];
[op setFreezable:YES];

[op onCompletion:^(MKNetworkOperation *completedOperation) {
   // ...
   // Here is where I process response and send the result to my completion block
   // It's called when WiFi is available, but not called otherwise.
   // ...
} onError:^(NSError *error) {
   // It's called when WiFi is available, but not called otherwise.
    DLog(@"Some error");
}];

[self enqueueOperation:op];

return op;

Answer 1

这是两个独立的问题:简历与完成.

1. resume: Freeze/Unfreeze机制仅在启用了缓存时才有效

   您必须在AppDelegate -didFinishLaunchingWithOptions中调用-useCache:

   self.networkEngine = [[MKNetworkEngine alloc] init ...];
   [self.networkEngine useCache]; // <- Add this line
   

2. complete:在网络状态更改时不会调用完成回调(即在Unfreeze之后)

   然而,如果您采取行动(1.)并在行中的MKNetworkOperation.m -checkAndRestoreFrozenOperations中放置一个断点:

   [self enqueueOperation:pendingOperation]
   

   您将发现在恢复网络连接时调用它,并且pendingOperation 是您的待处理POST.但是,由于新的MKNetworkOperation已经实例化(到那时完成块可能不再存在),onCompletion因此永远不会调用您的块.一种可能的解决方法是使用通知而不是回调.

3. 完全修复:比(2)更强大的方法可以在启动时^{}使用NSNotifications 替换块回调.尽早注册您的听众,就像在AppDelegate中一样.以下是使MKNetworkKit通知精通所需的最小更改:

   3A.在MKNetworkOperation.h中插入通知常量

   #define MKNetworkOperationCompletionNotification @"MKNetworkOperationCompletionNotification"
   #define MKNetworkOperationErrorNotification @"MKNetworkOperationErrorNotification"
   

   3B.在MKNetworkOperation.m -operationSucceeded中广播成功通知(请注意,我使用postNotificationOnMainThread,以便可以从主线程收听所述通知并更改UI;请参阅主线程上的NSOperation和NSNotificationCenter):

   -(void) operationSucceeded {
       NSDictionary * aUserInfo = [NSDictionary dictionaryWithObjectsAndKeys:
           self, NSStringFromClass([MKNetworkOperation class]),
           nil];
       NSNotification * notification = [NSNotification notificationWithName:MKNetworkOperationCompletionNotification
           object:nil
           userInfo:aUserInfo];
       [[NSNotificationCenter defaultCenter] postNotificationOnMainThread:notification];
       ...
   

   3C.在MKNetworkOperation.m -operationFailedWithError中广播失败通知

   -(void) operationFailedWithError:(NSError*) error {
       self.error = error;
       NSDictionary * aUserInfo = [NSDictionary dictionaryWithObjectsAndKeys:
           self,   NSStringFromClass([MKNetworkOperation class]),
           error,  NSStringFromClass([NSError class]),
           nil];
       NSNotification * notification = [NSNotification notificationWithName:MKNetworkOperationErrorNotification
           object:nil
           userInfo:aUserInfo];
   
       [[NSNotificationCenter defaultCenter] postNotificationOnMainThread:notification];
       ...
   

   3D.将一个相当持久的对象(如AppDelegate)注册为侦听器(不要忘记取消注册):

       // Listen to POST changes
       NSNotificationCenter *defaultCenter = [NSNotificationCenter defaultCenter];
       [defaultCenter addObserver:self
           selector:@selector(mkNetworkOperationCompletionNotification:)
           name:MKNetworkOperationCompletionNotification
           object:nil];
       [defaultCenter addObserver:self
           selector:@selector(mkNetworkOperationErrorNotification:)
           name:MKNetworkOperationErrorNotification
           object:nil];
   

   3E.监听器的示例代码:

   - (void)mkNetworkOperationCompletionNotification:(NSNotification*)notification {
       MKNetworkOperation *operation = [[notification userInfo]
           objectForKey:NSStringFromClass([MKNetworkOperation class])];
       NSLog(@"operationSucceeded: %@", [operation responseString]);
   }
   
   - (void)mkNetworkOperationErrorNotification:(NSNotification*)notification {
       NSError * error = [[notification userInfo] objectForKey:NSStringFromClass([NSError class])];
       NSLog(@"operationFailedWithError: %@", [error localizedDescription]);
   }
   

这样做,你已经完成了.X.

(编辑在上一个答案中删除了对MKNetworkOperation.h不必要的建议更改,并添加了第3段以显示如何克服^ {}限制.)