iOS Present modal view controller on startup without flash

Question

I\'d like to present modally, at first startup, a tutorial wizard to the user.

Is there a way to present a modal UIViewController on application startup

Answer 1

Bruce's answer pointed me in the right direction, but because my modal can appear more often than just on launch (it's a login screen, so it needs to appear if they log out), I didn't want to tie my overlay directly to the presentation of the view controller.

Here is the logic I came up with:

    self.window.rootViewController = _tabBarController;
    [self.window makeKeyAndVisible];

    WSILaunchImageView *launchImage = [WSILaunchImageView new];
    [self.window addSubview:launchImage];

    [UIView animateWithDuration:0.1f
                          delay:0.5f
                        options:0
                     animations:^{
                         launchImage.alpha = 0.0f;
                     } completion:^(BOOL finished) {
                         [launchImage removeFromSuperview];
                     }];

In a different section I perform the logic of presenting my login VC in the typical self.window.rootViewController presentViewController:... format which I can use regardless if it's an app launch or otherwise.

If anyone cares, here is how I created my overlay view:

@implementation WSILaunchImageView

- (instancetype)init
{
    self = [super initWithFrame:[UIScreen mainScreen].bounds];
    if (self) {
        self.image = WSILaunchImage();
    }
    return self;
}

And here's the logic for the launch image itself:

UIImage * WSILaunchImage()
{
    static UIImage *launchImage = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        if (WSIEnvironmentDeviceHas480hScreen()) launchImage = [UIImage imageNamed:@"LaunchImage-700"];
        else if (WSIEnvironmentDeviceHas568hScreen()) launchImage = [UIImage imageNamed:@"LaunchImage-700-568h"];
        else if (WSIEnvironmentDeviceHas667hScreen()) launchImage = [UIImage imageNamed:@"LaunchImage-800-667h"];
        else if (WSIEnvironmentDeviceHas736hScreen()) launchImage = [UIImage imageNamed:@"LaunchImage-800-Portrait-736h"];
    });
    return launchImage;
}

Aaaaand just for completion's sake, here is what those EnvironmentDevice methods look like:

static CGSize const kIPhone4Size = (CGSize){.width = 320.0f, .height = 480.0f};

BOOL WSIEnvironmentDeviceHas480hScreen(void)
{
    static BOOL result = NO;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        result = CGSizeEqualToSize([UIScreen mainScreen].bounds.size, kIPhone4Size);
    });
    return result;
}

Answer 2

may be your can use the "childViewController"

UIStoryboard *storyboard = self.window.rootViewController.storyboard;
TutorialViewController* tutorialViewController = [storyboard instantiateViewControllerWithIdentifier:@"tutorial"];

[self.window addSubview: tutorialViewController.view];
[self.window.rootViewController addChildViewController: tutorialViewController];

[self.window makeKeyAndVisible];

When you need to dismiss your tutor, you can remove its view from the superview. Also you can add some animation on the view by setting the alpha property.Hope helpful:)

Answer 3

let vc = UIViewController()
vc.modalPresentationStyle = .custom
vc.transitioningDelegate = noFlashTransitionDelegate
present(vc, animated: false, completion: nil)

class NoFlashTransitionDelegate: NSObject, UIViewControllerTransitioningDelegate {

    public func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
        if source.view.window == nil,
            let overlayViewController = UIStoryboard(name: "LaunchScreen", bundle: nil).instantiateInitialViewController(),
            let overlay = overlayViewController.view {
                source.view.addSubview(overlay)
                UIView.animate(withDuration: 0, animations: {}) { (finished) in
                    overlay.removeFromSuperview()
            }
        }
        return nil
    }
}