When you launch the LetsEat app, you'll immediately see the Explore screen. There is no way for the user to sign in. Due to this, you will need to implement a Sign In screen to allow the user to sign in. Initially, this Sign In screen will just display a button to allow the user to sign in in Guest mode, but you will add the Sign in with Apple button later. Follow these steps to do so:

1. Open the LetsEat project and build and run the app to make sure that it's working.
2. Go to Xcode | Preferences | Accounts and make sure that you have entered the Apple ID credentials for a paid Apple Developer account.
3. Click the LetsEat project in the Project navigator and click on Signing and Capabilities. Ensure the Team pop-up menu has been set for a paid Apple Developer account. If you get a Failed to register bundle identifier error, try changing the Bundle Identifier by adding some random characters to it, for example, com.12345.myname.LetsEat, and click the Try Again button:

4. Click on the + button:

5. The Object library will appear. Type sign into the filter field. You should see Sign in with Apple in the list of results. Double-click it.

6. Sign in with Apple has been added to the Signing and Capabilities screen:

7. If you see any errors appear, fix them before continuing by clicking on the appropriate buttons:

8. Click on Main.storyboard in the Project navigator and click the + button to display the Object library:

9. Type viewcon into the filter field. You will see a View Controller object as one of the results.
10. Drag it into the storyboard to the left of the Tab Bar Controller, as shown in the following screenshot:

11. Move the arrow indicating the initial View Controller from the Tab Bar Controller to the newly added View Controller:

12. Click the + button to display the Object Library. Type button into the filter field. You will see a Button object as one of the results.

13. Drag it into the view of the newly added View Controller:

14. Change the button text to Guest Mode:

15. Ctrl + Drag from the Guest Mode button to the Tab Bar Controller. Choose Present Modally from the pop-up menu:

16. A segue will be created between the View Controller and the Tab Bar Controller. Click the segue to select it:

17. In the Attributes inspector, set the Identifier to signin, set Presentation to Full Screen, and set Transition to Cross Dissolve:

18. Select the View of the View Controller in the document outline. In the Attributes inspector, set Background to Lets Eat Dark Grey:

19. Select the Guest Mode button in the document outline. In the Attributes inspector, set the Font to System Black 24.0:

20. Set the button's Text Color to System Red Color:

21. With the button selected, click the Add New Constraints button and add the following constraints:

• Left: 30
• Right: 30
• Bottom: 300

22. Build and run the app. Tap on the Guest Mode button:

23. The Explore screen will be displayed.

Now that you've implemented the Sign In screen, you have a place to display the Sign in with Apple button. You will implement a view controller for the Sign In screen with the necessary code to display the Sign in with Apple button in the next section.