iOS [Objective-C] 切换系统键盘

- (IBAction)switchKeyboard:(UIButton *)sender {
    // 对Button的操作
    sender.selected = !sender.selected;
    // 需要切换系统键盘
    self.numberTF.keyboardType = sender.selected ? UIKeyboardTypeDefault : UIKeyboardTypeNumberPad;
    // 切换键盘（重点）
    [self.numberTF reloadInputViews];
}