###textfield监听输入汉字数量

• 首先我们给textfield添加一个事件,当文字改变的时候调用

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

• 实现这个方法,监听输入汉字的数量

- (void)textFieldChange{        // 得到当前输入的文字    NSString *toBeString = self.nameTextField.text;    // 获取当前文字的类型    NSString *lang = [[UITextInputMode currentInputMode] primaryLanguage];    if([lang isEqualToString:@"zh-Hans"]){ //简体中文输入，包括简体拼音，健体五笔，简体手写        UITextRange *selectedRange = [self.nameTextField markedTextRange];        //获取高亮状态        UITextPosition *position = [self.nameTextField positionFromPosition:selectedRange.start offset:0];        if (!position){//非高亮            if (toBeString.length > 5) {                [UIAlertView alertViewWithTitle:@"提醒" message:@"名字长度不能超过5位" cancelButtonTitle:@"确定"];                                self.nameTextField.text = [toBeString substringToIndex:5];            }        }              }else{//中文输入法以外                 [UIAlertView alertViewWithTitle:@"提醒" message:@"名字只能输入中文" cancelButtonTitle:@"确定"];        self.nameTextField.text = [toBeString substringToIndex:toBeString.length - 1];      }     }