Question

I have code from Cocoa with Love that scrolls a UITextField when the keyboard comes up so that the keyboard does not cover the UITextField.

Here’s the code:

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    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;

    // Issue is that numerator isn't big enough for bottom 3rd of the screen

    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;

    NSLog(@"Midline: %g Fraction: %g / %g", midline, numerator, denominator);

    if (heightFraction < 0.0)
    {
        heightFraction = 0.0;
    }
    else if (heightFraction > 1.0)
    {
        heightFraction = 1.0;
    }

    UIInterfaceOrientation orientation =
    [[UIApplication sharedApplication] statusBarOrientation];
    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];
}

For debugging purposes I output the midline, etc to see what was happening. This is from tabbing from top to bottom. You can see about the 6th one down the numerator becomes negative, because the UITExtField.size.height that was converted for it’s parent view is a low number. I can’t figure out why the number would be a negative. The height should up just like all the others do as you go down the view.

2011-05-24 09:36:08.600 Baby Bloom[27794:207] Midline = 246 + 0.5 * 167

2011-05-24 09:36:08.601 Baby Bloom[27794:207] Midline: 329.5 Fraction: 22.3 / 409.6

2011-05-24 09:36:09.535 Baby Bloom[27794:207] Midline = 246 + 0.5 * 167

2011-05-24 09:36:09.536 Baby Bloom[27794:207] Midline: 329.5 Fraction: 22.3 / 409.6

2011-05-24 09:36:09.929 Baby Bloom[27794:207] Midline = 246 + 0.5 * 246

2011-05-24 09:36:09.930 Baby Bloom[27794:207] Midline: 369 Fraction: 61.8 / 409.6

2011-05-24 09:36:10.313 Baby Bloom[27794:207] Midline = 246 + 0.5 * 246

2011-05-24 09:36:10.314 Baby Bloom[27794:207] Midline: 369 Fraction: 61.8 / 409.6

2011-05-24 09:36:10.793 Baby Bloom[27794:207] Midline = 246 + 0.5 * 97

2011-05-24 09:36:10.794 Baby Bloom[27794:207] Midline: 294.5 Fraction: -12.7 / 409.6

2011-05-24 09:36:11.785 Baby Bloom[27794:207] Midline = 246 + 0.5 * 148

2011-05-24 09:36:11.786 Baby Bloom[27794:207] Midline: 320 Fraction: 12.8 / 409.6

Answer 1

Turns out that when in Landscape on the iPad it switches up the origin (x is now y and width is now height.

Here is the code to make it work:

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    CGRect textFieldRect = [self.view.window convertRect:textField.bounds fromView:textField];
    CGRect viewRect = [self.view.window convertRect:self.view.bounds fromView:self.view];

    float origin;
    float textFieldHeight;
    float viewOrigin;
    float viewHeight;

    UIInterfaceOrientation orientation =
    [[UIApplication sharedApplication] statusBarOrientation];


    if (orientation == UIInterfaceOrientationPortrait ||
        orientation == UIInterfaceOrientationPortraitUpsideDown)
    {
        textFieldHeight = textFieldRect.size.height;
        origin = textFieldRect.origin.y;
        viewOrigin = viewRect.origin.y;
        viewHeight = viewRect.size.height;
    }
    else
    {
        textFieldHeight = textFieldRect.size.width;
        viewOrigin = viewRect.origin.x;
        viewHeight = viewRect.size.width;
        origin = viewHeight - textFieldRect.origin.x;
    }


    CGFloat midline = origin + 0.5 * textFieldHeight;

    // Take the current middle y location of the textfield
    // If it is in the top 20% of the view don't move it
    // If it is in the middle 60% move it by a fraction of the keyboard size
    // If it is in the bottom 20% move it by the whole size of the keyboard


    CGFloat numerator = midline - viewOrigin - MINIMUM_SCROLL_FRACTION * viewHeight;

    CGFloat denominator = (MAXIMUM_SCROLL_FRACTION - MINIMUM_SCROLL_FRACTION) * viewHeight;

    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;

    //NSLog(@"Denom: %g", denominator);
    //NSLog(@"Distance: %g", animatedDistance);

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDuration:KEYBOARD_ANIMATION_DURATION];

    [self.view setFrame:viewFrame];

    [UIView commitAnimations];
}