Detect first launch

What do you mean first app launch ?

Is it the first time ever the user launches your app ?

Then you could keep this information in UserDefaults, with a property firstLaunch set to true

As soon as you launch, set the property to false.

But the splash screen usually shows each time you launch the app…

I Mean the first time the user launched the app and I have tried to use user defaults but it’s not working I’m probably doing it wrong is there a certain way to do it?

> I have tried to use user defaults but it’s not working

Describe 'not working' - what you did, what you expected, how those differed. Also how you're testing that event.

You should define in Root.plist, a key with firstLaunchKey identifier, set it to false

Then, in application(didFinishLaunching):

     let firstLaunchKey = "firstLaunchKey"
     let defaults = [firstLaunchKey: true]     // To have some value

     //  connects to Root.pList see: h ttps://makeapppie.com/2016/03/14/using-settings-bundles-with-swift/ 
        UserDefaults.standard.register(defaults: defaults)
        UserDefaults.standard.set(false, forKey: firstLaunchKey)     // Now, set to false

Try this simple code:

    if(![[NSUserDefaults standardUserDefaults] objectForKey:@"FirstLaunch"]) {
        [[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"FirstLaunch"];
        // the value doesn't matter - you are just testing to see if there is an object with the key "FirstLaunch"
        
        // execute code for first launch
    }else{
        // execute code for not first launch
    }

If your concern is for the user who deletes the app and then reinstalls it then you will need to use the keychain or the user's iCloud key-value file and both of those are a bit more complex.