swift3实时监听UITextField输入

实现代理方法

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

DLog(textField.text)

let tmpText = textField.text ?? ""

let newText = tmpText.replacingCharacters(in: range.toRange(string: tmpText), with: string)

DLog(newText.characters.count)

return true

}

扩展NSRange

extension NSRange {
   
        func toRange(string: String) -> Range<String.Index> {
            
            let startIndex = string.index(string.startIndex, offsetBy: self.location)
            let endIndex = string.index(startIndex, offsetBy: self.length)
            return startIndex..<endIndex
            
        }
 

}