Local notification in IOS app when app is background - xamarin.forms

Question

i want to send localnotification to my IOS app. App is checking time from my database when that time match to my mobile time it gives notification, but the problem that local notification works fine when my app is in foreground, when i close app local notification doesnt work any help will be appreciated
i have tried many things but couldnt succeed
here is my code i am running on App.cs
private async void CheckConnection()
{
var httpClient = new HttpClient();
var json = await httpClient.GetStringAsync("http://192.168.10.55:56556/api/ShowAll");
TimeSpan time = TimeSpan.FromSeconds(1);
DateTime dateTime = DateTime.Today.Add(time);
var admtPatients = Newtonsoft.Json.JsonConvert.DeserializeObject<List<ContactDetail>>(json);
ObservableCollection<ContactDetail> trends = new ObservableCollection<ContactDetail>(admtPatients);
foreach (var item in trends)
{
if (item.TimeSchedule == DateTime.Now.ToString("hh:mm:ss"))
{
CrossLocalNotifications.Current.Show("title", "body");
}
}
return;
}
protected override void OnStart()
{
var seconds = TimeSpan.FromSeconds(1);
Device.StartTimer(TimeSpan.FromSeconds(1), () =>
{
CheckConnection();
return true;
});
// Handle when your app starts
}
protected override void OnSleep()
{
base.OnSleep();
var seconds = TimeSpan.FromSeconds(1);
Device.StartTimer(TimeSpan.FromSeconds(1), () =>
{
CheckConnection();
return true;
});
}
protected override void OnResume()
{
base.OnSleep();
var seconds = TimeSpan.FromSeconds(1);
Device.StartTimer(TimeSpan.FromSeconds(1), () =>
{
CheckConnection();
return true;
});
}

Answer 1

When the user is not actively using your app, the system moves it to the background state. For many apps, the background state is just a brief stop on the way to the app being suspended. Suspending apps is a way of improving battery life it also allows the system to devote important system resources to the new foreground app that has drawn the user’s attention.
So ,if you want to start a long-running task when your app transitions to the background.You should request to start a background task includes an expiration handler just in case the task takes too long in your iOS project .
- (void)applicationDidEnterBackground:(UIApplication *)application
{
bgTask = [application beginBackgroundTaskWithName:#"MyTask" expirationHandler:^{
// Clean up any unfinished task business by marking where you
// stopped or ending the task outright.
[application endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
// Start the long-running task and return immediately.
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// Do the work associated with the task,you can use messageingcenter to told forms send notification.
[application endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
});
}