NSRange to Range

Question

How can I convert NSRange to Range in Swift?

I want to use the following UITextFieldDelegate method:

Answer 1

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

       let strString = ((textField.text)! as NSString).stringByReplacingCharactersInRange(range, withString: string)

 }

Answer 2

You need to use Range<String.Index> instead of the classic NSRange. The way I do it (maybe there is a better way) is by taking the string's String.Index a moving it with advance.

I don't know what range you are trying to replace, but let's pretend you want to replace the first 2 characters.

var start = textField.text.startIndex // Start at the string's start index
var end = advance(textField.text.startIndex, 2) // Take start index and advance 2 characters forward
var range: Range<String.Index> = Range<String.Index>(start: start,end: end)

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

Answer 3

I've found the cleanest swift2 only solution is to create a category on NSRange:

extension NSRange {
    func stringRangeForText(string: String) -> Range<String.Index> {
        let start = string.startIndex.advancedBy(self.location)
        let end = start.advancedBy(self.length)
        return Range<String.Index>(start: start, end: end)
    }
}

And then call it from for text field delegate function:

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let range = range.stringRangeForText(textField.text)
    let output = textField.text.stringByReplacingCharactersInRange(range, withString: string)

    // your code goes here....

    return true
}

Answer 4

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                                                                    

                                                        
            

Answer 5

extension StringProtocol where Index == String.Index {

    func nsRange(of string: String) -> NSRange? {
        guard let range = self.range(of: string) else {  return nil }
        return NSRange(range, in: self)
    }
}

Answer 6

The Swift 3.0 beta official documentation has provided its standard solution for this situation under the title String.UTF16View in section UTF16View Elements Match NSString Characters title