NSRange to Range

问题:

How can I convert NSRange to Range<String.Index> in Swift?

I want to use the following UITextFieldDelegate method:

    func textField(textField: UITextField!,
        shouldChangeCharactersInRange range: NSRange,
        replacementString string: String!) -> Bool {

textField.text.stringByReplacingCharactersInRange(???, withString: string)

回答1:

The NSString version (as opposed to Swift String) of replacingCharacters(in: NSRange, with: NSString) accepts an NSRange, so one simple solution is to convert String to NSString first. The delegate and replacement method names are slightly different in Swift 3 and 2, so depending on which Swift you\'re using:

Swift 3.0

func textField(_ textField: UITextField,
               shouldChangeCharactersIn range: NSRange,
               replacementString string: String) -> Bool {

  let nsString = textField.text as NSString?
  let newString = nsString?.replacingCharacters(in: range, with: string)
}

Swift 2.x

func textField(textField: UITextField,
               shouldChangeCharactersInRange range: NSRange,
               replacementString string: String) -> Bool {

    let nsString = textField.text as NSString?
    let newString = nsString?.stringByReplacingCharactersInRange(range, withString: string)
}

回答2:

As of Swift 4 (Xcode 9), the Swift standard library provides methods to convert between Swift string ranges (Range<String.Index>) and NSString ranges (NSRange). Example:

let str = \"a