Open the folder where your repo for Friends is located, and go into the ios folder. Open Friends.xcodeproj, which will automatically launch in Xcode.
In Xcode, go to the General tab for your project and select the Team drop-down menu under Signing. Sign in with your Apple ID and password. Once you do so, a Signing Certificate should be automatically generated for you.
Then, under Identity, set your Bundle Identifier to the App ID you previously added in the Apple Developer Portal. After this, we'll add an icon for the app. I've added icons that you can use for this reason in the repository belonging to this chapter.