sourceApplication
A key indicating that another app requested the launch of your app.
Declaration
static let sourceApplication: UIApplication.LaunchOptionsKeyDiscussion
The value of this key is an NSString object containing the bundle ID of the app that made the request. If the request originated from another app belonging to your team, UIKit sets the value of this key to the ID of that app. If the team identifier of the originating app is different than the team identifier of the current app, the value of the key is nil.
This key is also used to access the same value in the userInfo dictionary of the notification named didFinishLaunchingNotification.