UITableView header issues

headerview.m

#pragma mark - Class Methods

+ (BOOL)requiresConstraintBasedLayout {
	return YES;
}


#pragma mark - Init

- (id)initWithFrame:(CGRect)frame {

    self = [super initWithFrame:frame];

	if (!self) {
		return nil;
	}

	_imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"cloud-logo"]];
	_imageView.translatesAutoresizingMaskIntoConstraints = NO;
	_imageView.contentMode = UIViewContentModeRedraw;
	[_imageView setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisHorizontal];
	[_imageView setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical];
	[self addSubview:_imageView];

	_label = [VSSyncUI descriptionLabel];
	_label.translatesAutoresizingMaskIntoConstraints = NO;
	_label.text = NSLocalizedString(@"Vesper automatically keeps your notes backed up and shared across your devices. Sign in or create an account to get started. We’ll take care of the rest.", @"");
	_label.contentMode = UIViewContentModeRedraw;
	[_label setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisHorizontal];
	[_label setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical];

	[self addSubview:_label];

	[self setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisHorizontal];
	[self setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical];

	self.backgroundColor = [UIColor redColor];

	self.translatesAutoresizingMaskIntoConstraints = NO;
	
	return self;
}


#pragma mark - API

- (void)updateLabelWidth:(CGFloat)superviewWidth {

	self.label.preferredMaxLayoutWidth = superviewWidth - (20.0f * 2.0f);
}


#pragma mark - Constraints

- (void)updateConstraints {

	UIView *imageView = self.imageView;
	UIView *label = self.label;
	NSDictionary *bindings = NSDictionaryOfVariableBindings(imageView, label);

	NSLayoutConstraint *constraintCenterX = [NSLayoutConstraint constraintWithItem:self.imageView attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0.0];
	[self addConstraints:@[constraintCenterX]];

	NSArray *labelHorizontalConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"|-20-[label]-20-|" options:0 metrics:nil views:bindings];
	[self addConstraints:labelHorizontalConstraints];

	NSArray *verticalConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[imageView]-20-[label]-20-|" options:0 metrics:nil views:bindings];
	[self addConstraints:verticalConstraints];

	[super updateConstraints];
}

headerviewsetup.m

	UITableViewHeaderFooterView *headerView = [[UITableViewHeaderFooterView alloc] initWithReuseIdentifier:nil];
	CGRect appFrame = [UIScreen mainScreen].applicationFrame;
	VSSyncNoAccountHeaderView *headerViewContentView = [[VSSyncNoAccountHeaderView alloc] initWithFrame:CGRectMake(0.0, 0.0, CGRectGetWidth(appFrame), 400.0)];
	headerViewContentView.translatesAutoresizingMaskIntoConstraints = NO;
	[headerViewContentView updateLabelWidth:CGRectGetWidth(appFrame)];
	[headerViewContentView setNeedsUpdateConstraints];
	[headerViewContentView updateConstraintsIfNeeded];
	
//	CGSize bestSize = [headerViewContentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
////	bestSize.height += 20.0;
//	headerViewContentView.frame = CGRectMake(0.0, 0.0, CGRectGetWidth(appFrame), bestSize.height);

	[headerView.contentView addSubview:headerViewContentView];
	self.tableView.tableHeaderView = headerView;

What happens: the header view is too short. And it sits on top of the actual table view rows.

I get no messages about constraint issues. As far as I can tell, the constraints are fine.

You're not removing old constraints.

The setup part is happening in loadView in a UITableViewController subclass. No xibs or storyboards are involved.

@Inferis -- Good point, but right now I can verify that updateConstraints is called just once. So not removing constraints isn't the immediate issue.

Well, from what I can see, your headerView still has zero size, hence the problem. One possible approach is that you need to set constraints from headerViewContentView to headerView.contentView edges and call sizing method on headerView.

Yes, but it's possible that updateConstraints is called more than once (not sure this is happening here though). So you're add the same constraints each time updateConstraints is called.

Additionally: autolayout doesn't care about subviews and their sizes even if you applied constraints to them. You need to override intristicContentSize in the headerView class or set the dimensions to your instance manually.

Where do you add the constraints that relate headerViewContentView to its superview? The only constraints you create deal with the subviews of the VSSyncNoAccountHeaderView.

@kylesluder -- I did add those later. It didn’t actually help, though it changed the results slightly.

What does the implementation of -tableView:heightForHeaderInSection: look like? Are you returning the correct height from that? Could be an issue not with setting the correct size of the header view, but an incorrect content size on the table view's scroll view.

As pointed out by others above:

1. You need constrain headerViewContentView relative to headerView.contentView.
2. You didn't show your -tableView:heightForHeaderInSection:.

I also want to add that you'd better offer a minimum reproducible sample project so we don't need to guess what you did or not, right or wrong.

@brentsimmons Did you ever come up with a solution to this? I am currently trying to subclass UITableViewHeaderFooterView in order to display my own multi-line UILabel. It's just a mess, spent several hours with AutoLayout and Reveal debugging this.. UITableViewAutomaticDimension should work, the contentView has the correct size. But instead it sits on top of the 1st section cell which it overlaps.

@winkelsdorf Were you able to solve this on your side?