iOS UITextField 输入字数限制 去除虚拟键盘输入控制

解放代理，解放小键盘，从根本解决问题

[textField addTarget:self action:@selector(textChange:) forControlEvents:UIControlEventEditingChanged];

- (void)textChange:(UITextField*)textField {
    static const int Max_Text_Length = 5;
    //获取当前键盘类型
    UITextInputMode *mode = (UITextInputMode *)[UITextInputMode activeInputModes][0];
    //获取当前键盘语言
    NSString *lang = mode.primaryLanguage;
    if ([lang isEqualToString:@"zh-Hans"]) {//如果语言是汉语(拼音)
        //取到高亮部分范围
        UITextRange *selectedRange = [textField markedTextRange];
        //取到高亮部分
        UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
        //如果取不到高亮部分,代表没有拼音
        if (!position){//当期超过最大限制时
            if (textField.text.length > Max_Text_Length) {//对超出部分进行裁剪
                textField.text = [textField.text substringToIndex:Max_Text_Length];
            }
        }
    } else {//如果语言不是汉语,直接计算
        if (textField.text.length > Max_Text_Length) {
            textField.text = [textField.text substringToIndex:Max_Text_Length];
        }
    }
}