Could not insert new outlet connection: Could not find any information for the class named

Here are some things that can fix this (in increasing order of difficulty):

• Clean the project (Product > Clean)
• Manually paste in @IBOutlet weak var viewName: UIView! // or @IBAction func viewTapped(_ sender: Any) { } and control drag to it. (Change type as needed.) Also see this.
• Completely close Xcode and restart your project.
• Delete the Derived Data folder (Go to Xcode > Preferences > Locations and click the gray arrow by the Derived Data folder. Then delete your project folder.)
• Click delete on the class, remove reference (not Move to Trash), and add it back again. (see this answer)