Explicitly unwrapping optional nil does not cause crash

Question

A few folks asked this question before, yet no answer was accepted.

I have a UITableViewCell that contains a UITextField.

If I clic

Answer 1

One way to think this as a choise of the API Implementor. If implementor handles the input arguments it will not be any problem to the API User.

Lets create a drawing text class which just prints at console.

class TextDrawer {

  var mustBeText: String!

  func renderText(string: String) {
      print(string)
  }

  func renderSafely() {
     renderText(string: self.mustBeText ?? "Nothing found to be rendered")
     // or 
     if let safeString = self.mustBeText {
        renderText(string: safeString)
     }
  }

  func renderUnsafely() {
      renderText(string: mustBeText)
  }
}

We have defined the mustBeText as String! means we are allowed to expect any string as well as nil argument.

Now, as we create a instance of the class as below:

let textDrawer = TextDrawer()
textDrawer.mustBeText = nil // this is allowed since the `mustBeText` is `String!`.

textDrawer.renderSafely() // prints -- Nothing found to be rendered

textDrawer.renderUnsafely() // crashes at runtime.

The renderUnsafaly() will crash since its not handling the nil case.