iphone - XMPPFramework 后台 UILocalNotification 支持没有 VoIP plist 键

Question

我正在尝试使用 XMPPFramework 在应用程序终止之前在“10 分钟窗口”中显示背景通知。似乎所有网络请求都在后台排队，xmppStream:didReceiveMessage:直到应用程序回到前台才被调用。

我注意到像动词这样的应用程序支持这种行为。它们显然不是 VoIP 应用程序，所以我很好奇它们是如何实现这种行为的。

Answer 1

如果其他人遇到此问题，您可以通过将此代码添加到您的 App Delegate 来解决它。如果您想查看，我的完整源代码在这里：OTRAppDelegate.m。其他相关代码在OTRBuddy.m的 receiveMessage: 中。

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    NSLog(@"Application entered background state.");
    NSAssert(self.backgroundTask == UIBackgroundTaskInvalid, nil);
    self.didShowDisconnectionWarning = NO;

    self.backgroundTask = [application beginBackgroundTaskWithExpirationHandler: ^{
        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"Background task expired");
            if (self.backgroundTimer) 
            {
                [self.backgroundTimer invalidate];
                self.backgroundTimer = nil;
            }
            [application endBackgroundTask:self.backgroundTask];
            self.backgroundTask = UIBackgroundTaskInvalid;
        });
    }];

    dispatch_async(dispatch_get_main_queue(), ^{
        self.backgroundTimer = [NSTimer scheduledTimerWithTimeInterval:10 target:self selector:@selector(timerUpdate:) userInfo:nil repeats:YES];
    });
}

- (void) timerUpdate:(NSTimer*)timer {
    UIApplication *application = [UIApplication sharedApplication];

    NSLog(@"Timer update, background time left: %f", application.backgroundTimeRemaining);

    if ([application backgroundTimeRemaining] < 60 && !self.didShowDisconnectionWarning) 
    {
        UILocalNotification *localNotif = [[UILocalNotification alloc] init];
        if (localNotif) {
            localNotif.alertBody = EXPIRATION_STRING;
            localNotif.alertAction = OK_STRING;
            [application presentLocalNotificationNow:localNotif];
        }
        self.didShowDisconnectionWarning = YES;
    }
    if ([application backgroundTimeRemaining] < 10) 
    {
        // Clean up here
        [self.backgroundTimer invalidate];
        self.backgroundTimer = nil;
        [application endBackgroundTask:self.backgroundTask];
        self.backgroundTask = UIBackgroundTaskInvalid;
    }
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{

}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    /*
     Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
     */
    NSLog(@"Application became active");
    if (self.backgroundTimer) 
    {
        [self.backgroundTimer invalidate];
        self.backgroundTimer = nil;
    }
    if (self.backgroundTask != UIBackgroundTaskInvalid) 
    {
        [application endBackgroundTask:self.backgroundTask];
        self.backgroundTask = UIBackgroundTaskInvalid;
    }

    application.applicationIconBadgeNumber = 0;
}