ios – 当可达性改变时,MKNetworkKit操作不会恢复/完成

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

情况如下：

>我禁用WiFi并运行应用程序.
>即使没有可达性,我也通过从MKNetworkEngine子类创建MKNetworkOperation来请求(使用POST)一些数据.在请求数据之前,操作被设置为freezable(根据Mugunth Kumar’s doc).
>启用WiFi后,调用MKNetworkEngine中的checkAndRestoreFrozenOperations,它会检测到有一个挂起的操作(创建一个没有可达性的操作),它会尝试入队.
>之后,我的onCompletion块永远不会被调用.

关于冻结MKNetworkKit中的操作可达性,有什么我不明白的吗？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;

解决方法

这是两个独立的问题：简历与完成.

> resume：Freeze / Unfreeze机制仅在启用缓存时有效

您必须在AppDelegate -didFinishLaunchingWithOptions中调用-useCache：

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

>完成：网络状态更改时(即解冻后)不会调用完成回调

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,由于已经实例化了新的MKNetworkOperation(并且到那时完成块可能不再存在),因此永远不会调用onCompletion块.一种可能的解决方法是使用通知而不是回调.
>完全修复：一种比(2)更强大的方法可以在启动之间工作,即用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NSOperation and NSNotificationCenter on the main thread)：

-(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,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.)