Correct way to have a one time login iPhone? - iphone

Question

I'm trying to create an app that will require a login upon first time load. Once the user logged in successfully the credentials will be stored in a keychain so the user doesn't have to keep logging in.
Here is a quick mockup of the following code I've written; Is using the AppDelegate the correct way to go about handling which View to show first?
AppDelegate.h
#import <UIKit/UIKit.h>
#import "KeychainItemWrapper.h"
#import "ViewController.h"
#import "TestBViewController.h"
#import "User.h"
#interface AppDelegate : UIResponder <UIApplicationDelegate>
#property (strong, nonatomic) UIWindow *window;
#property (strong, nonatomic) TestBViewController *mainVC; // User see's after loggin in
#property (strong, nonatomic) User *user;
#property (strong, nonatomic) KeychainItemWrapper *keychainItem;
- (void)saveKeychainUsername:(NSString *)username andPassword:(NSString *)password;
- (void)loadLoggedInViewControllers;
#end
AppDelegate.m
#import "AppDelegate.h"
#implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.keychainItem = [[KeychainItemWrapper alloc] initWithIdentifier:#"AppUniqueID" accessGroup:nil];
// [self.keychainItem resetKeychainItem];
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"MainStoryboard" bundle:nil];
// Override point for customization after application launch.
NSString *password = [self.keychainItem objectForKey:(__bridge id)(kSecValueData)];
NSString *username = [self.keychainItem objectForKey:(__bridge id)(kSecAttrAccount)];
NSLog(#"username: %#, password: %#", username, password);
if ([username length] <= 0 || [password length] <= 0) {
// Login VC
ViewController *loginVC = (ViewController *)[mainStoryboard instantiateViewControllerWithIdentifier:#"Login"];
self.window.rootViewController = loginVC;
} else {
[self loadLoggedInViewControllers];
}
return YES;
}
- (void)loadLoggedInViewControllers {
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"MainStoryboard" bundle:nil];
// Attempt to login user
self.user = [[User alloc] init];
self.user.name = #"Bob";
self.user.hasAccess = YES;
// If user is no longer valid (for whatever reason) remove his keychain information so we can save the new ones.
// Valid user! Skip Login VC
self.mainVC = (TestBViewController *)[mainStoryboard instantiateViewControllerWithIdentifier:#"Main"];
self.mainVC.user = self.user;
self.window.rootViewController = self.mainVC;
}
ViewController.m - Think of this as my LoginViewController
- (IBAction)storePassButtonTap:(id)sender {
if ([[username text] length] > 0 && [[password text] length] > 0) {
AppDelegate *shareDelegate = [[UIApplication sharedApplication] delegate];
[shareDelegate saveKeychainUsername:[username text] andPassword:[password text]];
[shareDelegate loadLoggedInViewControllers];
} else {
if ([[username text] length] <= 0) {
// Error message
}
if ([[password text] length] <= 0) {
// Error message
}
}
}

Answer 1

I wont recommend doing this. I have done this in the past and I have faced problems such as the orientation delegates were not working once I change the rootviewcontroller property of appdelegate like this. Looks like it is fixed in iOS 6, but my understanding is that this is something unusual and not supposed to do.
Instead have a dummy viewcontroller as rootviewcontroller and add other viewcontrollers as its childViewController. You can remove and add any view controller this way.

Answer 2

Personally I wouldn't. I use storyboards and would set a view controller as the root. If I need to do this I would leave the view controller blank (maybe have an activity indicator if it takes a minute to login), run the login code here and then either move to the login segue or the main app segue.
Making sure that both the next screens hide the back button so the user can't go back to this screen.
I like the leave the appDeleage for things like reestablishing tcp connections and closing them when entering background.