I go over some code written by other developers and now and then I encounter signatures like this one:

func didReceiveLogMessage(_ message: String!)

Would it be safe to convert this parameter type to String instead of String! ?

CodePudding user response：

Basically never declare a custom function parameter as implicit unwrapped optional. Don't.

This is a pre Swift 3 legacy syntax only for Objective-C and Core Foundation compatibility.

It's absolutely safe and even highly recommended to remove the exclamation mark. However if you really need an optional use a regular optional (?)

CodePudding user response：

This gives no value. It actually adds complexity as even an Inmplicitly unwrapped optional as such counts as an optional, meaning it can be nil (but will crash). a regular String can't be nil