如何在所有界面方向的键盘上方显示文本字段

Question

In my iPhone app i used the following code to lift the view in order to show the textfield above the keyboard. My application support all four interface orientations. I use the following code to lift the view. Problem here is that it only works for portrait orientation. Is there any way to implement the correct lifting in all four orientations

static const CGFloat KEYBOARD_ANIMATION_DURATION = 0.3;
static const CGFloat MINIMUM_SCROLL_FRACTION = 0.2;
static const CGFloat MAXIMUM_SCROLL_FRACTION = 0.8;
static const CGFloat PORTRAIT_KEYBOARD_HEIGHT = 216;
static const CGFloat LANDSCAPE_KEYBOARD_HEIGHT = 162;

- (void)textFieldDidBeginEditing:(UITextField *)textField {
    UIInterfaceOrientation orientation =    [Globals getUIInterfaceOrientation];//[[UIApplication sharedApplication] statusBarOrientation];
    CGRect textFieldRect = [self.view.window convertRect:textField.bounds fromView:textField];
    CGRect viewRect = [self.view.window convertRect:self.view.bounds fromView:self.view];   

    CGFloat midline = textFieldRect.origin.y + 0.5 * textFieldRect.size.height;
    CGFloat numerator = midline - viewRect.origin.y - MINIMUM_SCROLL_FRACTION * viewRect.size.height;
    CGFloat denominator = (MAXIMUM_SCROLL_FRACTION - MINIMUM_SCROLL_FRACTION) * viewRect.size.height;   
    CGFloat heightFraction = numerator / denominator;

    if (heightFraction < 0.0) {
        heightFraction = 0.0;
    }
    else if (heightFraction > 1.0) {
        heightFraction = 1.0;
    }   
    if (orientation == UIInterfaceOrientationPortrait || orientation == UIInterfaceOrientationPortraitUpsideDown) 
        animatedDistance = floor(PORTRAIT_KEYBOARD_HEIGHT * heightFraction);
    else 
        animatedDistance = floor(LANDSCAPE_KEYBOARD_HEIGHT * heightFraction);
    CGRect viewFrame = self.view.frame;
    viewFrame.origin.y -= animatedDistance;
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDuration:KEYBOARD_ANIMATION_DURATION];
    [self.view setFrame:viewFrame];    
    [UIView commitAnimations];  
}

- (void)textFieldDidEndEditing:(UITextField *)textField{
    CGRect viewFrame = self.view.frame;
    viewFrame.origin.y += animatedDistance;
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDuration:KEYBOARD_ANIMATION_DURATION];
    [self.view setFrame:viewFrame];    
    [UIView commitAnimations];      
}

Answer 1

The following is how I currently achieve this on all my apps.

The trick here is that although the view is aware of the orientation, the keyboard is not. This means in Landscape, the keyboards width is actually its height and visa versa.

To modify Apples recommended way of changing the content insets and get it support landscape orientation, I would recommend using the following:

// Call this method somewhere in your view controller setup code.
- (void)registerForKeyboardNotifications
{
    [[NSNotificationCenter defaultCenter] addObserver:self
            selector:@selector(keyboardWasShown:)
            name:UIKeyboardDidShowNotification object:nil];
   [[NSNotificationCenter defaultCenter] addObserver:self
             selector:@selector(keyboardWillBeHidden:)
             name:UIKeyboardWillHideNotification object:nil];
}

// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
    UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation];
    CGSize keyboardSize = [[[notif userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    if (orientation == UIDeviceOrientationLandscapeLeft || orientation == UIDeviceOrientationLandscapeRight ) {
        CGSize origKeySize = keyboardSize;
        keyboardSize.height = origKeySize.width;
        keyboardSize.width = origKeySize.height;
    }
    UIEdgeInsets contentInsets = UIEdgeInsetsMake(0, 0, keyboardSize.height, 0);
    scroller.contentInset = contentInsets;
    scroller.scrollIndicatorInsets = contentInsets;

    // If active text field is hidden by keyboard, scroll it so it's visible
    // Your application might not need or want this behavior.
    CGRect rect = scroller.frame;
    rect.size.height -= keyboardSize.height;
    NSLog(@"Rect Size Height: %f", rect.size.height);

    if (!CGRectContainsPoint(rect, activeField.frame.origin)) {
        CGPoint point = CGPointMake(0, activeField.frame.origin.y - keyboardSize.height);
        NSLog(@"Point Height: %f", point.y);
        [scroller setContentOffset:point animated:YES];
    }
}

// Called when the UIKeyboardWillHideNotification is sent    
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
    UIEdgeInsets contentInsets = UIEdgeInsetsZero;
    scrollView.contentInset = contentInsets;
    scrollView.scrollIndicatorInsets = contentInsets;
}

---

The part to pay attention to here is the following:

UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation];
CGSize keyboardSize = [[[notif userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
if (orientation == UIDeviceOrientationLandscapeLeft || orientation == UIDeviceOrientationLandscapeRight ) {
    CGSize origKeySize = keyboardSize;
    keyboardSize.height = origKeySize.width;
    keyboardSize.width = origKeySize.height;
}

What is does, is detects what orientation the device is in. If it is landscape, it will 'swap' the width and height values of the keyboardSize variable to ensure that the correct values are being used in each orientation.

Answer 2

Probably you want to use Keyboard notifications shown in this Text and Web Programming Guide for the iOS Document, See Listing 2-1 2-2 2-3

You can get keyboard size when receiving the notification.