presentViewController over TabBarController causes "attempt to present *VC on TabBarVC whose view is not in the window hierarchy" - presentmodalviewcontroller

Question

My root view controller is a Tab Bar Controller loaded in the delegate. Each of the tabs is a table view controller. When the application is first loaded I want a login screen to popup via presentViewController, which I have in my viewDidLoad method of the Tab Bar Controller. It results in the window hierarchy error that I have read about - though none of the solutions have worked for me. I tried instead presenting the modal view in the viewDidLoad method of the first tab but this resulted in the same error.
In my tab bar view controller in viewDidLoad, my code is:
CLLoginViewController *loginVC = [[CLLoginViewController alloc] init];
loginVC.delegate = self;
[self.view addSubview:loginVC.view];
[self presentViewController:loginVC animated:NO completion:nil];

Answer 1

Your question is quite vague but what i have understood, You want to present a login screen before the tabController is loaded.
So a better way would be, In your AppDelegate when setting rootViewController of window, do something like this
if([[NSUserDefaults standardUserDefaults] boolForKey:#"showTabBar"]){
self.window.rootViewController = tabBarControllerObject; //TabBarView is loaded
[[NSUserDefaults standardUserDefaults] setBool:YES forKey:#"showTabBar"];
}
else{
self.window.rootViewController = tabBarControllerObject; //Login Screen is loaded for first time.
}
Hope this helps