UITextFiled时时获取当前输入的字符长度

  //创建一个对象

  UITextFiled *textFiled = [UITextFiled alloc] init];

  //给对象关联一个方法，ps：UIControlEventEditingChanged (当文本控件中的文本被改变时发送通知。)

  [textFiled addTarget:self action:@selector(textFieldChange:) forControlEvents:UIControlEventEditingChanged];

  //这个是对象关联的方法

  -(void)textFieldChange:(UITextField *)textField
{
    UILabel *line = nil;
    if ([textField isEqual:_currentPwdTextF]) {
        line = _line1;
    }else if ([textField isEqual:_newPwdTextF]){
        line = _line2;
    }else if ([textField isEqual:_againPwdTextF]){
        line = _line3;
    }
    
    if (textField.text.length >= 6 && textField.text.length <= 16) {
        line.backgroundColor = [UIColor colorWithRed:0.070 green:1.000 blue:0.930 alpha:1.000];
    }
    else{
        line.backgroundColor = RED_COLOR;
    }

}

the end