Customize View Controller Stack on didFinishLaunching - ios

Question

I am trying to present a tutorial/login/introduction view controller for my app on first launch using the following code:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
UIViewController *firstController = [[UIViewController alloc] init];
[self.window setRootViewController:firstController];
if ([self shouldShowIntro]) {
IntroViewController *introViewController = [[IntroViewController alloc] init];
[firstController presentViewController:introViewController animated:NO completion:nil];
}
return YES;
}
This works fine, but there is an annoying visual effect that takes place... Before you see the IntroViewController, there is a split second where the firstController is visible. I tried presenting the IntroViewController before setting the rootViewController of the window, but this (not surprisingly) results in the following warning:
Warning: Attempt to present <IntroViewController: 0x7fd8eb3362f0> on <UIViewController: 0x7fd8eb335180> whose view is not in the window hierarchy!
How can I modally present the IntroViewController without this annoying visual flash? I want IntroViewController to already be showing after the launch screen disappears and be able to be dismissed modally.

Answer 1

The following works for me with no flicker running on iOS 8.1 on an iPhone 6 and in the simulator. I used SDK version 8.1 and I think your SDK level is different because I got different warnings and results than you using your provided code.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
UIViewController *firstController = [[UIViewController alloc] init];
firstController.view.backgroundColor = [UIColor blueColor];
[self.window setRootViewController:firstController];
dispatch_async(dispatch_get_main_queue(), ^{
UIViewController* modalViewController = [[UIViewController alloc] init];
modalViewController.view.backgroundColor = [UIColor grayColor];
[firstController presentViewController: modalViewController animated: NO completion: nil];
});
// dismiss after a few seconds..
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[firstController dismissViewControllerAnimated: YES completion: nil];
});
return YES;
}
Update with MMDrawerController:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
MMDrawerController *drawerController = [[MMDrawerController alloc] init];
drawerController.centerViewController = [[UIViewController alloc] init];
drawerController.centerViewController.view.backgroundColor = [UIColor blueColor];
drawerController.rightDrawerViewController = [[UIViewController alloc] init];
drawerController.rightDrawerViewController.view.backgroundColor = [UIColor greenColor];
drawerController.openDrawerGestureModeMask = MMOpenDrawerGestureModeAll;
drawerController.closeDrawerGestureModeMask = MMOpenDrawerGestureModeAll;
[self.window setRootViewController:drawerController];
dispatch_async(dispatch_get_main_queue(), ^{
UIViewController* modalViewController = [[UIViewController alloc] init];
modalViewController.view.backgroundColor = [UIColor grayColor];
[drawerController presentViewController: modalViewController animated: NO completion: nil];
});
// dismiss after a few seconds..
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[drawerController dismissViewControllerAnimated: YES completion: nil];
});
return YES;
}
Also, per you comment it sounds as if having the pre-loaded view is key. Try invoking [firstController view] and [modalController view] before you present to ensure they're loaded.

Answer 2

try moving this line below the code where you set your view controllers.
[self.window makeKeyAndVisible];
something like this:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.window.backgroundColor = [UIColor whiteColor];
UIViewController *firstController = [[UIViewController alloc] init];
[self.window setRootViewController:firstController];
if ([self shouldShowIntro]) {
IntroViewController *introViewController = [[IntroViewController alloc] init];
[firstController presentViewController:introViewController animated:NO completion:nil];
}
[self.window makeKeyAndVisible];
return YES
}

Answer 3

Put
if ([self shouldShowIntro]) {
IntroViewController *introViewController = [[IntroViewController alloc] init];
[firstController presentViewController:introViewController animated:NO completion:nil];
}
in to the viewDidAppear function of FirstViewController rather than in the AppDelegate. That should suppress the warning and perform the operation smoothly.