类似于这个问题:iPad: Detecting External Keyboard ，我正在开发一个 iPad 应用程序，它使用带有自定义 inputAccessoryView 的文本字段来为虚拟键盘提供额外的功能。

但是，如果硬件键盘(例如蓝牙键盘)连接到设备，则软件键盘不会按预期显示，但出于某种原因，inputAccessoryView 仍然可见 在屏幕底部。此外，这似乎会导致触发 UIKeyboardDidShowNotification(因此向上移动我的 View 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，但它们都在收到 UIKeyboardDidShowNotification 后检查状态，此时 inputAccessoryView 已经可见(例如 How can I detect if an external keyboard is present on an iPad? )。

如果没有连接硬件键盘，我正在寻找一种只显示 inputAccessoryView 的方法。因此，我需要知道是否在 触发 UIKeyboardDidShowNotification 之前连接了硬件键盘。

此处提供的公认解决方案 How can I detect if an external keyboard is present on an iPad?对我来说没有选择，因为他们使用私有(private) API，这可能会导致我的应用被拒绝。

最佳答案

这只是@arlomedia 回答的增强版。我所做的是监视 willShow 和 didShow。

我用来将 TextView 移动到适当位置的 willShow，以便它以与键盘相同的速度移动。

我使用的 didShow 使用上述技术检查键盘的外观尺寸并相应地隐藏/显示 accessoryInputView。

重要的，我还将该 View 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;
}

注意 编辑以添加对 userInteractionEnabled 的更改，以便隐藏的 accessoryView 不会消耗水龙头。

关于ios - 如果连接了硬件键盘，则隐藏 inputAccessoryView，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27830857/