Changes

By default, the Assistant Editor will be in Automatic mode, whereby it automatically attempts to display the correct source file based on the currently selected item in Interface Builder. If the correct file is not displayed, use the toolbar along the top of the editor panel to select the correct file. The small instance of the Assistant Editor icon in this toolbar can be used to switch to Manual mode allowing the file to be selected from a pull-right menu containing all the source files in the project.

Make sure that the ViewController.swift file is displayed in the Assistant Editor and establish an outlet for the Text Field object by Ctrl-clicking on the Text Field object in the view and dragging the resulting line to the area immediately beneath the class declaration line in the Assistant Editor panel as illustrated in Figure 16-8: