如果连接了硬件键盘，则隐藏 inputAccessoryView

Question

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，但由于某种原因，inputAccessoryView 仍然可见 em> 在屏幕底部。此外，即使使用硬件键盘进行输入，这似乎也会导致触发UIKeyboardDidShowNotification（因此向上移动我的视图以避免被实际上不存在的键盘遮挡）。

我找到了几种检测是否连接了硬件键盘的解决方案，但它们都在收到UIKeyboardDidShowNotification 之后检查状态，此时 inputAccessoryView 已经可见（例如How can I detect if an external keyboard is present on an iPad? ）。

我正在寻找一种仅在未连接硬件键盘时才显示 inputAccessoryView 的方法。因此，我需要知道是否在UIKeyboardDidShowNotification 被触发之前连接了硬件键盘。

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

Answer 1

IIRC，当软件键盘出现时，视图不会自行调整大小。我正在调整 UIKeyboardDidShow 通知触发的 keyboardDidShow 方法中的视图大小。因此，以该方法检测硬件与软件键盘就足够了，然后您可以跳过调整表格大小并隐藏输入附件视图（或调整表格大小以适应输入附件视图，如果您希望保持可见） )。

为了正确调整视图大小（无论是否存在硬件键盘），我改编了来自 this answer 的代码：

- (void)keyboardDidShow:(NSNotification *)aNotification {
    CGRect keyboardBeginFrame = [[[aNotification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue];
    CGRect keyboardEndFrame = [[[aNotification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    float keyboardHeight = 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

    // now you can resize your views based on keyboardHeight
    // that will be the height of the inputAccessoryView if a hardware keyboard is present
}

如果您想让 inputAccessoryView 可见，这就是您所需要的。为了隐藏它，我认为您需要设置一个实例变量，以便您可以在 keyboardDidShow 中访问它：

UIView *currentInputAccessoryView;

- (void)textFieldDidBeginEditing:(UITextField *)textField {
    self.currentInputAccessoryView = textField.inputAccessoryView;
}

- (void)textViewDidBeginEditing:(UITextView *)textView {
    self.currentInputAccessoryView = textView.inputAccessoryView;
}

- (void)keyboardDidShow:(NSNotification *)aNotification {
    CGRect keyboardBeginFrame = [[[aNotification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue];
    CGRect keyboardEndFrame = [[[aNotification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    float keyboardHeight = 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

    if (keyboardHeight == 44) {
        self.currentInputAccessoryView.hidden = YES;
        keyboardHeight = 0;
    }

    // now you can resize your views based on keyboardHeight
    // that will be 0 if a hardware keyboard is present
}

Answer 2

这只是@arlomedia 对答案的增强。我所做的是观看 willShow 和 didShow。

我用来将我的文本视图移动到适当位置的 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表观大小并相应地隐藏/显示附件输入视图。

重要的是我还将该视图设置为默认隐藏，并且当接收到 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;
}

注意已编辑以向 userInteractionEnabled 添加更改，以便隐藏的附件视图不吃水龙头。

Answer 3

我最后解决这个问题的方法是简单地为UIKeyboardWillShowNotification 添加一个观察者...

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillShow:)
                                             name:UIKeyboardWillShowNotification object:nil];

.. 并隐藏之前存储在实例变量中的inputAccessoryView。

// Called when the UIKeyboardWillShowNotification is sent.
- (void)keyboardWillShow:(NSNotification*)notification
{
    NSLog(@"keyboardWillShow");

    // get the frame end user info key
    CGRect kbEndFrame = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];

    // calculate the visible portion of the keyboard on the screen
    CGFloat height = [[UIScreen mainScreen] bounds].size.height - kbEndFrame.origin.y;

    // check if there is a input accessorry view (and no keyboard visible, e.g. hardware keyboard)
    if (self.activeTextField && height <= self.activeTextField.inputAccessoryView.frame.size.height) {

        NSLog(@"hardware keyboard");

        self.activeTextField.inputAccessoryView.hidden = YES;
    } else {

        NSLog(@"software keyboard");

        self.activeTextField.inputAccessoryView.hidden = NO;
    }
}

原来问题是由我在其 getter 方法中动态创建自定义 UITextField 子类的 inputAccessoryView 引起的。我无意中在每次调用 getter 时 重新创建 视图，而不是通过延迟实例化重用实例变量。这导致我对视图的所有分配都被忽略了，因为当访问文本字段并显示键盘时，getter 方法将被调用多次，因此视图一直被覆盖 在我的任务之后。 重用视图通过将其保存到实例变量来解决此问题。