Presenting a local notification immediately while running in the background

chuanyituoku

于 2014-08-30 19:40:32 发布

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分类专栏： PushNotification

本文链接：https://blog.youkuaiyun.com/chuanyituoku/article/details/38946489

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本文介绍了一种在iOS应用进入后台时实现聊天消息推送的方法。通过开始后台任务并利用剩余的后台运行时间检查是否有新的聊天消息，若有则使用本地通知的形式告知用户。此方法能够有效提升用户体验。

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- (void)applicationDidEnterBackground:(UIApplication *)application {
      NSLog(@"Application entered background state.");
      // bgTask is a property of the class
      NSAssert(self.bgTask == UIInvalidBackgroundTask, nil);
      bgTask = [application beginBackgroundTaskWithExpirationHandler: ^{
          dispatch_async(dispatch_get_main_queue(), ^{
              [application endBackgroundTask:self.bgTask];
              self.bgTask = UIInvalidBackgroundTask;
          });
}];
      dispatch_async(dispatch_get_main_queue(), ^{
          while ([application backgroundTimeRemaining] > 1.0) {
init];
friend];
nil);
NSString *friend = [self checkForIncomingChat];
if (friend) {
    UILocalNotification *localNotif = [[UILocalNotification alloc]
    if (localNotif) {
        localNotif.alertBody = [NSString stringWithFormat:
            NSLocalizedString(@"%@ has a message for you.", nil),
        localNotif.alertAction = NSLocalizedString(@"Read Message",
        localNotif.soundName = @"alarmsound.caf";
        localNotif.applicationIconBadgeNumber = 1;

                      [application presentLocalNotificationNow:localNotif];
                      [localNotif release];
                      friend = nil;
                      break;
} }
          }
          [application endBackgroundTask:self.bgTask];
          self.bgTask = UIInvalidBackgroundTask;
});
}