This blog post illustrates how deep linking into an iOS app works.

DeepLinking means that you can enter e.g. the following link in Safari or any other browser on iPhone or iPad:

app://mycustomcontroller/1234?showIt=true

This should open a defined part of the app. Therefore first the following function in AppDelegate must be implemented:

func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey: Any] = [:]) -> Bool {
        logVerbose("application:openUrl:", tag: "openUrl")
        return env.deepLinkHandler.handleUrl(url, animated: false)
    }

and that deeplink must be handled:

public func handleUrl(_ url: URL, animated: Bool) -> Bool {
  let deepLink = DeepLink(url: url)
}

public struct DeepLink {

public init?(string: String) {
        guard let url = URL(string: string) else { return nil }

        guard let components = URLComponents(url: url, resolvingAgainstBaseURL: true) else { return nil }        
…
        if components.hasFeature("mycustomcontroller") {

guard let queryItems = components.queryItems else {
            return nil
        }

queryItems.forEach { item in

…
}
            route = .mycustomcontroller(url.lastPathComponent)
            return
        }
…
    }
}

...