How to resize a tableHeaderView of a UITableView?

Question

I'm having trouble resizing a tableHeaderView. It simple doesn't work.

1) Create a UITableView and UIView (100 x 320 px);

2) Set the UIView as tableHeaderView of the UITableView;

3) Build and Go. Everything is ok.

Now, I want to resizing the tableHeaderView, so I add this code in viewDidLoad:

self.tableView.autoresizesSubviews = YES;

self.tableView.tableHeaderView = myHeaderView;
self.tableView.tableFooterView = myFooterView;

CGRect newFrame = self.tableView.tableHeaderView.frame;
newFrame.size.height = newFrame.size.height + 100;
self.tableView.tableHeaderView.frame = newFrame;

The height of the tableHeaderView should appear with 200, but appears with 100.

If I write:

self.tableView.autoresizesSubviews = YES;


CGRect newFrame = myHeaderView.frame;
newFrame.size.height = newFrame.size.height + 100;
myHeaderView.frame = newFrame;


self.tableView.tableHeaderView = myHeaderView;
self.tableView.tableFooterView = myFooterView;

Then it starts with 200 of height, as I want. But I want to be able to modify it in runtime.

I've also tried this, without success:

self.tableView.autoresizesSubviews = YES;

self.tableView.tableHeaderView = myHeaderView;
self.tableView.tableFooterView = myFooterView;

CGRect newFrame = self.tableView.tableHeaderView.frame;
newFrame.size.height = newFrame.size.height + 100;
self.tableView.tableHeaderView.frame = newFrame;

[self.tableView.tableHeaderView setNeedsLayout];
[self.tableView.tableHeaderView setNeedsDisplay];
[self.tableView setNeedsLayout];
[self.tableView setNeedsDisplay];

The point here is: How do we resize a tableHeaderView in runtime ???

Have anyone able to do this?

Thanks

iMe

Answer 1

This answer is old and apparently doesn't work on iOS 7 and above.

I ran into the same problem, and I also wanted the changes to animate, so I made a subclass of UIView for my header view and added these methods:

- (void)adjustTableHeaderHeight:(NSUInteger)newHeight{
    NSUInteger oldHeight = self.frame.size.height;
    NSInteger originChange = oldHeight - newHeight;

    [UIView beginAnimations:nil context:nil];

    [UIView setAnimationDuration:1.0f];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)];

    self.frame = CGRectMake(self.frame.origin.x, 
                        self.frame.origin.y, 
                        self.frame.size.width, 
                        newHeight);

    for (UIView *view in [(UITableView *)self.superview subviews]) {
        if ([view isKindOfClass:[self class]]) {
            continue;
        }
        view.frame = CGRectMake(view.frame.origin.x, 
                            view.frame.origin.y - originChange, 
                            view.frame.size.width, 
                            view.frame.size.height);
    }

    [UIView commitAnimations];
}

- (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context{
    [(UITableView *)self.superview setTableHeaderView:self];
}

This essentially animates all the subviews of the UITableView that aren't the same class type as the calling class. At the end of the animation, it calls setTableHeaderView on the superview (the UITableView) – without this the UITableView contents will jump back the next time the user scrolls. The only limitation I've found on this so far is if the user attempts to scroll the UITableView while the animation is taking place, the scrolling will animate as if the header view hasn't been resized (not a big deal if the animation is quick).

Answer 2

FYI: I've gotten this to work by modifying the tableHeaderView and re-setting it. In this case, i'm adjusting the size of the tableHeaderView when the UIWebView subview has finished loading.

[webView sizeToFit];
CGRect newFrame = headerView.frame;
newFrame.size.height = newFrame.size.height + webView.frame.size.height;
headerView.frame = newFrame;
[self.tableView setTableHeaderView:headerView];

Answer 3

If you want to conditionally animate the changes you can do the following:

- (void) showHeader:(BOOL)show animated:(BOOL)animated{

    CGRect closedFrame = CGRectMake(0, 0, self.view.frame.size.width, 0);
    CGRect newFrame = show?self.initialFrame:closedFrame;

    if(animated){
        // The UIView animation block handles the animation of our header view
        [UIView beginAnimations:nil context:nil];
        [UIView setAnimationDuration:0.3];
        [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];

        // beginUpdates and endUpdates trigger the animation of our cells
        [self.tableView beginUpdates];
    }

    self.headerView.frame = newFrame;
    [self.tableView setTableHeaderView:self.headerView];

    if(animated){
        [self.tableView endUpdates];
        [UIView commitAnimations];
    }
}

Please note that the animation is two-folded:

1. The animation of the cells below the tableHeaderView. This is done using beginUpdates and endUpdates
2. The animation of the actual header view. This is done using a UIView animation block.

In order to synchronize those two animations the animationCurve has to be set to UIViewAnimationCurveEaseInOut and the duration to 0.3, which seems to be what the UITableView uses for it's animation.

Update

I created an Xcode project on gihub, which does this. Check out the project ResizeTableHeaderViewAnimated in besi/ios-quickies