如何正确使用"openParentApplication"和"handleWatchKitExtensionRequest"以便调用"reply()"？

Question

情况:我openParentApplication在Watch应用程序handleWatchKitExtensionRequest中使用主应用程序.这在模拟器中运行良好,当iPhone应用程序处于活动/打开状态时,它也适用于实际设备(Apple Watch和iPhone).

问题:当我在实际设备(Apple Watch和iPhone)上运行它时,如果主iPhone应用程序未处于活动/打开状态,handleWatchKitExtensionRequest则不会返回数据openParentApplication.

WatchKit扩展中的InterfaceController.m中的代码:

NSDictionary *requst = @{ @"request" : @"getData" };
[InterfaceController openParentApplication:requst
                                     reply:^( NSDictionary *replyInfo, NSError *error ) {
                                        // do something with the returned info
                                     }];

iPhone主应用程序的app代理中的代码:

- (void)application:(UIApplication *)application handleWatchKitExtensionRequest:(NSDictionary *)userInfo reply:(void ( ^)( NSDictionary * ))reply
{
  if ( [[userInfo objectForKey:@"request"] isEqualToString:@"getData"] )
  {
    // get data
    // ...
    reply( data );
  }
}

Answer 1

当iPhone上的主应用程序未处于活动状态时,reply()可能无法访问,因为之前操作系统已将后台任务杀死.

解决方案是显式启动文档中handleWatchKitExtensionRequest指定的后台任务.如果后台任务是这样启动的,它最多可以运行180秒.这可以确保iPhone上的主应用程序在发送回复之前不会被暂停.

iPhone主应用程序的app代理中的代码:

- (void)application:(UIApplication *)application handleWatchKitExtensionRequest:(NSDictionary *)userInfo reply:(void ( ^)( NSDictionary * ))reply
{
   __block UIBackgroundTaskIdentifier watchKitHandler;
   watchKitHandler = [[UIApplication sharedApplication] beginBackgroundTaskWithName:@"backgroundTask"
                                                               expirationHandler:^{
                                                                 watchKitHandler = UIBackgroundTaskInvalid;
                                                               }];

   if ( [[userInfo objectForKey:@"request"] isEqualToString:@"getData"] )
   {
      // get data
      // ...
      reply( data );
   }

   dispatch_after( dispatch_time( DISPATCH_TIME_NOW, (int64_t)NSEC_PER_SEC * 1 ), dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0 ), ^{
      [[UIApplication sharedApplication] endBackgroundTask:watchKitHandler];
   } );
}

如果您需要异步获取数据,请使用以下方法确保该方法不立即返回(不调用回复):

- (void)application:(UIApplication *)application handleWatchKitExtensionRequest:(NSDictionary *)userInfo reply:(void ( ^)( NSDictionary * ))reply
{ 
    __block UIBackgroundTaskIdentifier watchKitHandler;

    watchKitHandler = [[UIApplication sharedApplication] beginBackgroundTaskWithName:@"backgroundTask"
                                                               expirationHandler:^{
                                                                   watchKitHandler = UIBackgroundTaskInvalid;
                                                               }];  

   NSMutableDictionary *response = [NSMutableDictionary dictionary];

   dispatch_semaphore_t sema = dispatch_semaphore_create(0);

   [ClassObject getDataWithBlock:^(BOOL succeeded, NSError *error){

        if (succeeded)
        {
            [response setObject:@"update succeded" forKey:@"updateKey"];
        }
        else
        {
            if (error)
            {
                [response setObject:[NSString stringWithFormat:@"update failed: %@", error.description] forKey:@"updateKey"]; 
            }
            else
            {
                [response setObject:@"update failed with no error" forKey:@"updateKey"];
            }
        }

        reply(response);
        dispatch_semaphore_signal(sema);
    }];

    dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);

    dispatch_after(dispatch_time( DISPATCH_TIME_NOW, (int64_t)NSEC_PER_SEC * 1), dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    [[UIApplication sharedApplication] endBackgroundTask:watchKitHandler];
  });
}