如果连接了硬件键盘，则隐藏 inputAccessoryView

类似于这个问题：iPad：检测外接键盘 https://stackoverflow.com/questions/5019471/ipad-detecting-external-keyboard，我正在开发一个 iPad 应用程序，该应用程序使用文本字段和自定义inputAccessoryView为虚拟键盘提供附加功能。

然而，如果一个硬件键盘（例如蓝牙键盘）连接到设备，软件键盘未按预期显示，但由于某种原因 inputAccessoryView 是仍然可见在屏幕底部。此外，这似乎会导致解雇UIKeyboardDidShowNotification（因此将我的视图向上移动以避免被实际上不存在的键盘遮挡）即使使用硬件键盘进行输入也是如此。

我找到了几种检测硬件键盘是否已连接的解决方案，但它们都检查状态after收到一个UIKeyboardDidShowNotification，此时 inputAccessoryView 已经可见（例如如何检测 iPad 上是否存在外接键盘？ https://stackoverflow.com/questions/2893267/how-can-i-detect-if-an-external-keyboard-is-present-on-an-ipad).

我正在寻找一种仅在没有连接硬件键盘的情况下显示 inputAccessoryView 的方法。因此我需要知道是否连接了硬件键盘before a UIKeyboardDidShowNotification被解雇了。

此处提供的已接受的解决方案如何检测 iPad 上是否存在外接键盘？ https://stackoverflow.com/questions/2893267/how-can-i-detect-if-an-external-keyboard-is-present-on-an-ipad对我来说没有选择，因为它们使用私有 API，这可能会导致我的应用程序被拒绝。

这只是@arlomedia 答案的增强。我所做的就是观察 willShow 和 didShow。

我用 willShow 将文本视图移动到位，以便它以与键盘相同的速度移动。

我使用 didShow 使用上述技术检查键盘的外观大小，并相应地隐藏/显示accessoryInputView。

这一点很重要我还将该视图设置为默认隐藏，并且当收到 willHide 事件时，它会再次隐藏。

- (void) addKeyboardObserver {
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardHidden:) name:UIKeyboardWillHideNotification object:nil];
}

- (void) removeKeyboardObserver {
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
}

- (void)keyboardWillShow:(NSNotification*)notification {
    CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;

    // If we're on iOS7 or earlier and landscape then the height is in the
    // width.
    //
    if ((IS_LANDSCAPE == YES) && (IS_IOS8_OR_LATER == NO)) {
        keyboardSize.height = keyboardSize.width;
    }

    NSNumber *rate = notification.userInfo[UIKeyboardAnimationDurationUserInfoKey];

    CGRect textFieldFrame = self.textField.frame;
    textFieldFrame.origin.y = ([Util screenHeight] - keyboardSize.height) - textFieldFrame.size.height - [Util scaledHeight:10.0];

    // Move the text field into place.
    //
    [UIView animateWithDuration:rate.floatValue animations:^{
        self.answerTextField.frame = textFieldFrame;
    }];

    keyboardShown = YES;
}

- (void)keyboardDidShow:(NSNotification*)notification {
    CGRect keyboardBeginFrame = [[[notification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue];
    CGRect keyboardEndFrame = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    CGSize keyboardSize = keyboardBeginFrame.size;

    // If we're on iOS7 or earlier and landscape then the height is in the
    // width.
    //
    if ((IS_LANDSCAPE == YES) && (IS_IOS8_OR_LATER == NO)) {
        keyboardSize.height = ABS(keyboardBeginFrame.origin.x - keyboardEndFrame.origin.x); // the keyboard will move by an amount equal to its height when it appears; ABS is needed for upside-down orientations
    } else {
        keyboardSize.height = ABS(keyboardBeginFrame.origin.y - keyboardEndFrame.origin.y); // the keyboard will move by an amount equal to its height when it appears; ABS is needed for upside-down orientations
    }

    NSNumber *rate = notification.userInfo[UIKeyboardAnimationDurationUserInfoKey];

    [UIView animateWithDuration:rate.floatValue animations:^{
        if (keyboardSize.height <= self.accessoryBar.frame.size.height) {
            self.textField.inputAccessoryView.hidden = YES;
            self.answerTextField.inputAccessoryView.userInteractionEnabled = NO;
        } else {
            self.textField.inputAccessoryView.hidden = NO;
            self.answerTextField.inputAccessoryView.userInteractionEnabled = YES;
        }
    }];

    keyboardShown = YES;
}

- (void)keyboardHidden:(NSNotification*)notification {

    NSNumber *rate = notification.userInfo[UIKeyboardAnimationDurationUserInfoKey];

    // Remove/hide the accessory view so that next time the text field gets focus, if a hardware
    // keyboard is used, the accessory bar is not shown.
    //
    [UIView animateWithDuration:rate.floatValue animations:^{
        self.textField.inputAccessoryView.hidden = YES;
        self.answerTextField.inputAccessoryView.userInteractionEnabled = NO;
    }];

    keyboardShown = NO;
}

NOTE编辑以添加对 userInteractionEnabled 的更改，以便隐藏的accessoryView不会吃水龙头。