autolayout constraints in nib not honored for UITableViewHeaderFooterView

Question

I have a UITableView with several columns of data. The reusable cells are loaded from an xib file which has the appropriate labels and autolayout constraints. Everything works perfectly; the table columns are laid out correctly on different devices and when the devices are rotated.

The problem I am having is trying to create a table footer to show the totals of the columns in the table.

I created an xib file with the same autolayout constraints as the cell xib file and am loading it in tableView.viewForFooterInSection the same way I did for the cells. As required, I am using a subclass of UITableViewHeaderFooterView instead of UITableViewCell.

The awakeFromNib method in the UITableViewHeaderFooterView subclass sets the background color, so I can see that it is the correct size on all devices/orientation, but the labels from the footer xib file are not getting laid out to match the table cells.

The autolayout constraints from the footer xib file are not being honored. When I set a different background color in the footer xib file, the table footer shows this background color for the length of the xib's view.

I'm new to all of this technology and would greatly appreciate help in resolving this incredibly frustrating issue.

Is there a way to use autolayout for UITableViewHeaderFooterViews loaded from nibs?

Answer 1

You should call setNeedsUpdateConstraints() to update your view.

From apple documentation

Controls whether the view’s constraints need updating. When a property of your custom view changes in a way that would impact constraints, you can call this method to indicate that the constraints need to be updated at some point in the future. The system will then call updateConstraints as part of its normal layout pass. Updating constraints all at once just before they are needed ensures that you don’t needlessly recalculate constraints when multiple changes are made to your view in between layout passes.

Also, you can update view throw layoutSubviews()

Lays out subviews. The default implementation of this method does nothing on iOS 5.1 and earlier. Otherwise, the default implementation uses any constraints you have set to determine the size and position of any subviews. Subclasses can override this method as needed to perform more precise layout of their subviews. You should override this method only if the autoresizing and constraint-based behaviors of the subviews do not offer the behavior you want. You can use your implementation to set the frame rectangles of your subviews directly. You should not call this method directly. If you want to force a layout update, call the setNeedsLayout method instead to do so prior to the next drawing update. If you want to update the layout of your views immediately, call the layoutIfNeeded method.