presence: unsubscribe when app is in background

Change-Id: Ie15efebd03ea57e1ba9b7c33c406ac4e940a75ae

Ring/Ring/AppDelegate.swift

@@ -240,16 +240,21 @@ class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterD
     }
 
     func reloadDataFor(account: AccountModel) {
+        let state = UIApplication.shared.applicationState
+        if state == .active {
             self.contactsService.loadContacts(withAccount: account)
             self.contactsService.loadContactRequests(withAccount: account.id)
             self.presenceService.subscribeBuddies(withAccount: account.id, withContacts: self.contactsService.contacts.value, subscribe: true)
             self.conversationManager?
                     .prepareConversationsForAccount(accountId: account.id)
         }
+    }
 
     func applicationDidEnterBackground(_ application: UIApplication) {
         self.log.warning("entering background")
         self.callService.muteCurrentCallVideoVideo( mute: true)
+        guard let account = self.accountService.currentAccount else { return }
+        self.presenceService.subscribeBuddies(withAccount: account.id, withContacts: self.contactsService.contacts.value, subscribe: false)
     }
 
     func applicationWillEnterForeground(_ application: UIApplication) {
@@ -257,6 +262,8 @@ class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterD
         self.daemonService.connectivityChanged()
         self.updateNotificationAvailability()
         self.callService.muteCurrentCallVideoVideo( mute: false)
+        guard let account = self.accountService.currentAccount else { return }
+        self.presenceService.subscribeBuddies(withAccount: account.id, withContacts: self.contactsService.contacts.value, subscribe: true)
     }
 
     func applicationWillTerminate(_ application: UIApplication) {