Erase fields when application goes back to foreground - ios

Question

I'm a very beginner in iOS developpment. What I what to do is to delete the content of 2 fields (login and password) when application moves to foregroung after being in background.
To be clear: if a user put the application in foreground and is on the login screen, fields corrsponding to login and password should be empty.
What I have done: I have add a listener to the AppDelegate file that is detecting well background/foreground actions. Here is the code:
- (void)applicationWillEnterForeground:(UIApplication *)application {
#try {
UINavigationController *navigationController = (UINavigationController*)self.window.rootViewController;
UIViewController *cont = [[navigationController viewControllers] objectAtIndex:[navigationController viewControllers].count - 1];
if ([cont isKindOfClass:[LoginScreenController class]]){
NSLog(#"[AppDelegate] ok, we're on login screen");
}
else {
NSLog(#"[AppDelegate] No, we're not");
}
}
#catch(NSException *exp)
{
NSLog(#"[AppDelegate] Fail: %#",exp);
}
}
But when executing the code, I reach an issue linked to BaseRootView... First, do I proceed the appropriate way and then, how to do what I want to do? That's to say, how to erease the fields (I have a function to do this in the LoginController class, so how to call it prperly?)
Thanks !

Answer 1

Put your code in
- (void)applicationDidBecomeActive:(UIApplication *)application
You should use this method instead of
- (void)applicationWillEnterForeground:(UIApplication *)application
when you update user interface this is what this method is for.
Hope this help.
// EXTENDED
Can you try put this code to UIApplicationDidBecomeActiveNotification:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(updateUI)
name:UIApplicationDidBecomeActiveNotification
object:nil];
And add this code to AppDelegate:
-(void)dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidBecomeActiveNotification object:nil];
}
and add:
-(void)updateUI
{
//Add code to update ui
}

Answer 2

You can do this by posting a notification. Here in the place of yourFunctionName write your function name which is to erase the fields
In login view controller write this following code.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self)
{
// Custom initialization
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(yourFunctionName) name:#"removeText" object:nil];
}
return self;
}
Now post a notification in applicationWillEnterForeground method.
- (void)applicationWillEnterForeground:(UIApplication *)application
{
[[NSNotificationCenter defaultCenter] postNotificationName:#"removeText" object:nil];
}
Hope this helps you.