ios - 一个接一个调用两个NSURLSessionTask完成 block ？

Question

我有以下使用 AFNetworking 调用我的服务器的设置。我使用了在 Internet 上找到的一个示例来包含一个完成 block ，这样我就知道调用何时结束。

文件“FCEngine.m”

- (void)fetchBusinessProfile:(NSString *)userID userAccessToken:(NSString *)userAccessToken completion:(void (^)(NSDictionary *json, BOOL success))completion {

/// Validate the user token again the user id.

NSDictionary *parameters = [[NSDictionary alloc]initWithObjectsAndKeys:userAccessToken,@"user_access_token",
                            userID,@"user_id",
                            nil];


AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];

AFHTTPRequestSerializer *serializer = [AFHTTPRequestSerializer serializer];
manager.requestSerializer = serializer;

manager.responseSerializer = [AFJSONResponseSerializer serializerWithReadingOptions:NSJSONReadingAllowFragments];

[manager POST:@"" parameters:parameters progress:nil success:^(NSURLSessionTask *task, id responseObject) {

    NSLog(@"JSON Business Profile: %@", responseObject);

    fetchBusinessProfileCompletion(responseObject, YES);

} failure:^(NSURLSessionTask *operation, NSError *error) {

    //NSLog(@"Error: %@", error);

    NSMutableDictionary *errorResponse = [[NSMutableDictionary alloc] init];

    [errorResponse setObject:@"connection_error" forKey:@"state"];
    [errorResponse setObject:[error localizedDescription] forKey:@"description"];

    fetchBusinessProfileCompletion(errorResponse, YES);

}];

}

- (void)fetchNotifications:(NSString *)userID userAccessToken:(NSString *)userAccessToken completion:(void (^)(NSDictionary *json, BOOL success))completion {

/// Validate the user token again the user id.

NSDictionary *parameters = [[NSDictionary alloc]initWithObjectsAndKeys:userAccessToken,@"user_access_token",
                            userID,@"user_id",
                            nil];


AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];

AFHTTPRequestSerializer *serializer = [AFHTTPRequestSerializer serializer];
manager.requestSerializer = serializer;

manager.responseSerializer = [AFJSONResponseSerializer serializerWithReadingOptions:NSJSONReadingAllowFragments];

[manager POST:@"" parameters:parameters progress:nil success:^(NSURLSessionTask *task, id responseObject) {

    //NSLog(@"JSON: %@", responseObject);

    completion(responseObject, YES);

} failure:^(NSURLSessionTask *operation, NSError *error) {

    //NSLog(@"Error: %@", error);

    NSMutableDictionary *errorResponse = [[NSMutableDictionary alloc] init];

    [errorResponse setObject:@"connection_error" forKey:@"state"];
    [errorResponse setObject:[error localizedDescription] forKey:@"description"];

    completion(errorResponse, YES);

}];


}

以下是我如何调用Main View Controller

- (void)MyMethods {

 [self.fcEngine fetchBusinessProfile:userID userAccessToken:userAccessToken completion:^(NSDictionary *json, BOOL success) {

    /// Response here


}];

[self.fcEngine fetchNotifications:self.userID userAccessToken:self.userAccessToken completion:^(NSDictionary *json, BOOL success) {

       //// Response here

 }];

}

现在的问题是 2 个调用是一个接一个地进行的，当我为一个调用获取数据时，例如“fetchBusinessProfile”两者上的竞争 block 都被调用。

我是不是设置错了？如果有 2 个或多个调用，我只希望为该特定 block 调用完成，而不是全部调用。

Answer 1

我认为您不了解异步和完成 block 。如果您按照上面的定义进行 2 个网络调用，它们可以按任何顺序发生。 fetchBusinessProfile 和 fetchNotifications 中的completion 将是不同 completion blocks ... unless你让它们一样。

例如:

 [self.fcEngine fetchBusinessProfile:userID userAccessToken:userAccessToken completion:^(NSDictionary *json, BOOL success) {

    /// Handle response
    // Note calling the SAME completion block
    sameCompletionBlockAlreadyDefined();


}];

[self.fcEngine fetchNotifications:self.userID userAccessToken:self.userAccessToken completion:^(NSDictionary *json, BOOL success) {

    //// Handle response
    // Note calling the SAME completion block
    sameCompletionBlockAlreadyDefined();

 }];

在这种情况下，sameCompletionBlockAlreadyDefined() 是一些已经定义的 block 。在这种情况下，每个调用的 block 主体确实是，但通过 sameCompletionBlockAlreadyDefined 漏斗到同一调用。您可能会感到困惑，因为 completion 在您的第一个代码段中恰好被命名为相同。

请注意，您的问题措辞非常糟糕，因此并不完全清楚您的意思。

更大的问题是您的目标是什么？您希望最后只调用一个完成 block 吗？或者您想要完全不同的完成 block ？两者都需要不同的技术。明确您的目标是什么。

前者是使用 dispatch_group 提供的最佳服务。后者需要不同的完成 block 。

调度组的示例如下:

dispatch_group_t group = dispatch_group_create();

dispatch_group_enter(group);

[self.fcEngine fetchBusinessProfile:userID userAccessToken:userAccessToken completion:^(NSDictionary *json, BOOL success) {

    /// Handle response
    dispatch_group_leave(group);


];

self.fcEngine fetchNotifications:self.userID userAccessToken:self.userAccessToken completion:^(NSDictionary *json, BOOL success) {

    //// Handle response
    dispatch_group_leave(group);

}];

dispatch_group_wait(group, DISPATCH_TIME_FOREVER);

// This would be some completion block which means all is done
completion();