//假设限制输入10个字
let wordNum = 10
fileprivate lazy var textTF:UITextField = {
let textTF = UITextField(frame: CGRect(x: 10, y: 50, width: 300, height: 50))
textTF.addTarget(self, action: #selector(textFieldChange), for: .editingChanged)
textTF.backgroundColor = .cyan
return textTF
}()
@objc func textFieldChange(_ titleTF: UITextField) {
if titleTF.markedTextRange != nil {return}
guard var genString = titleTF.text else {return}
if genString.count > wordNum{
let startIdx = genString.startIndex
let endIdx = genString.index(genString.startIndex, offsetBy: wordNum-1)
genString =String(genString[startIdx...endIdx])
}
titleTF.text = genString
}
//" 去掉首尾空格 和 尾部换行 ".trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
