You can check all types of notifications cf this question:
BOOL remoteNotificationsEnabled, noneEnabled,alertsEnabled, badgesEnabled, soundsEnabled = NO;
// iOS8+
if ([[UIApplication sharedApplication] respondsToSelector:@selector(registerUserNotificationSettings:)]) {
remoteNotificationsEnabled = [UIApplication sharedApplication].isRegisteredForRemoteNotifications;
UIUserNotificationSettings *userNotificationSettings = [UIApplication sharedApplication].currentUserNotificationSettings;
noneEnabled = userNotificationSettings.types == UIUserNotificationTypeNone;
alertsEnabled = userNotificationSettings.types & UIUserNotificationTypeAlert;
badgesEnabled = userNotificationSettings.types & UIUserNotificationTypeBadge;
soundsEnabled = userNotificationSettings.types & UIUserNotificationTypeSound;
}
else { // iOS 7 and below
UIRemoteNotificationType enabledRemoteNotificationTypes = [UIApplication sharedApplication].enabledRemoteNotificationTypes;
noneEnabled = enabledRemoteNotificationTypes == UIRemoteNotificationTypeNone;
alertsEnabled = enabledRemoteNotificationTypes & UIRemoteNotificationTypeAlert;
badgesEnabled = enabledRemoteNotificationTypes & UIRemoteNotificationTypeBadge;
soundsEnabled = enabledRemoteNotificationTypes & UIRemoteNotificationTypeSound;
}
Then depending of the results, update your boolean on your backend by making a call to your API.