This code uses UIApplication.shared.canOpenURL to see if there's an app to handle cydia://, the popular Jailbroken package manager app.
Since iOS 9, apps must include any non-system URL scheme they will test with canOpenURL in the LSApplicationQueriesSchemes ("Queried URL Schemes") field in their Info.plist. Without this, the checking of canOpenURL cydia:// will always return false.
