Error with notification names while converting code to Swift 4.2

nsnotifications xcode10 swift4.2
mannyCalavera picture mannyCalavera · Sep 23, 2018 · Viewed 12.2k times · Source

The code below was working fine before Swift 4.2:

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillChange(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)

When I click the 'Fix' option, it becomes:

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillChange(notification:)), name: NSNotification.Name.UIResponder.keyboardWillShowNotification, object: nil)

But it is still marked an error. Here is the explanation:

Type 'NSNotification.Name' has no member 'UIResponder'

And then I tried to delete 'UIResponder':

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillChange(notification:)), name: NSNotification.Name.

...but I don't know how should I complete it.

Answer

Tamás Sengel picture Tamás Sengel · Sep 23, 2018

The correct form is:

UIResponder.keyboardWillShowNotification

...so, your code becomes:

NotificationCenter.default.addObserver(
    self, 
    selector: #selector(keyboardWillChange(notification:)), 
    name: UIResponder.keyboardWillShowNotification, 
    object: nil
)

This is a known issue with Xcode 10. Automatic Fix-it is not working correctly for Swift 4.2 when it comes to correcting notification names.

In Swift 4.2, lots of Notification.Name instances became instance variables in other classes. For example, keyboardWillShowNotification is now an instance variable of UIResponder.

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