首先需要继承 UITextFieldDelegate
class TestViewController: UIViewController,UITextFieldDelegate{
}
添加事件委托
textField.delegate = self
点击输入框时触发以下事件：
func textFieldDidBeginEditing(_ textField: UITextField){
}
我的需求为输入一百以内最多为两位小数，使用以下方式对输入的值进行实时监控
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
var newString = (textField.text! as NSString).replacingCharacters(in: range, with: string)
let expression = "^[0-9]*(?:\\.[0-9]{0,2})?$"
do {
let regex: NSRegularExpression = try NSRegularExpression(pattern: expression, options: NSRegularExpression.Options.caseInsensitive)
let numberOfMatches = regex.matches(in: newString, options: NSRegularExpression.MatchingOptions.reportProgress, range: NSMakeRange(0, newString.characters.count))
if numberOfMatches.count == 0{
return false
}else{
if newString != "" {
if newString[newString.startIndex] == "." {
newString = "0" + newString
}
if newString[newString.index(before: newString.endIndex)] == "." {
newString = newString + "0"
}
if (Double(newString)! > 100.0){
account_textfield.text = "100"
return false
}
}
return true
}
}
catch {
return false
}
}
通过return值对输入框的值进行控制，return false则放弃编辑，输入框内容不会变更