Objective C: Changing tab bar controller index through NSNotificationCenter causes problems - ios

Question

I have a table view. when a certain row is selected (log out button), a check is done for any current sync going on between server and iPhone. If it is still syncing, I use an observer in viewDidLoad to notify me when it finishes. The observer then calls logMeOut. If it is not syncing, logMeOut is called immediately.
Changing tab index works perfectly fine when called in didSelectRowAtIndexPath. But when called from the NSNotificationObserver, I can see that both the tabs at index 0 and 3 are highlighted blue (which means somehow the system selected index 0, but failed to cancel index 3). The page is not changed; it still displays the same page at index 3. I can't go to index 0 by tapping the tab. I have to tap one of the indexes 1-3 and then tap index 0 again to navigate there.
Setting breakpoints and logging statements show that NSNotificationCenter is called correctly. I tested this on both iPhone and Xcode Simulator.
//When called from observer
//when called from didselectrowatindexpath
- (void)viewDidLoad
{
[super viewDidLoad];
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(logMeOut) //does not work when called here
name:#"canLogOutNow"
object:nil];
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
[self.tableView deselectRowAtIndexPath:indexPath animated:YES];
if (indexPath.row == 0) {
SyncEngine *syncengine = [SyncEngine sharedEngine];
if (![syncengine syncInProgress]) {
[self logMeOut];//works fine when called here
} else {
syncengine.needToLogOut = YES; //tells sync engine to call notification center
}
}
}
- (void)logMeOut {
[PFUser logOut];
[self.parentViewController.tabBarController setSelectedIndex:0]; //Current index is 3
}
//snippet of syncengine.m
if (self.needToLogOut) {
NSNotification *notification = [NSNotification notificationWithName:#"canLogOutNow" object:nil];
[[NSNotificationCenter defaultCenter] postNotification:notification];
}