How do I set the height of tableHeaderView (UITableView) with autolayout?

Solution 1:

You need to use the UIView systemLayoutSizeFittingSize: method to obtain the minimum bounding size of your header view.

I provide further discussion on using this API in this Q/A:

How to resize superview to fit all subviews with autolayout?

Solution 2:

I've found an elegant way to way to use auto layout to resize table headers, with and without animation.

Simply add this to your View Controller.

func sizeHeaderToFit(tableView: UITableView) {
    if let headerView = tableView.tableHeaderView {
        let height = headerView.systemLayoutSizeFittingSize(UILayoutFittingCompressedSize).height
        var frame = headerView.frame
        frame.size.height = height
        headerView.frame = frame
        tableView.tableHeaderView = headerView
        headerView.setNeedsLayout()
        headerView.layoutIfNeeded()
    }
}

To resize according to a dynamically changing label:

@IBAction func addMoreText(sender: AnyObject) {
    self.label.text = self.label.text! + "\nThis header can dynamically resize according to its contents."
}

override func viewDidLayoutSubviews() {
    // viewDidLayoutSubviews is called when labels change.
    super.viewDidLayoutSubviews()
    sizeHeaderToFit(tableView)
}

To animate a resize according to a changes in a constraint:

@IBOutlet weak var makeThisTallerHeight: NSLayoutConstraint!

@IBAction func makeThisTaller(sender: AnyObject) {

    UIView.animateWithDuration(0.3) {
        self.tableView.beginUpdates()
        self.makeThisTallerHeight.constant += 20
        self.sizeHeaderToFit(self.tableView)
        self.tableView.endUpdates()
    }
}

See the AutoResizingHeader project to see this in action. https://github.com/p-sun/Swift2-iOS9-UI

Solution 3:

I really battled with this one and plonking the setup into viewDidLoad didn't work for me since the frame is not set in viewDidLoad, I also ended up with tons of messy warnings where the encapsulated auto layout height of the header was being reduced to 0. I only noticed the issue on iPad when presenting a tableView in a Form presentation.

What solved the issue for me was setting the tableViewHeader in viewWillLayoutSubviews rather than in viewDidLoad.

func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        if tableView.tableViewHeaderView == nil {
            let header: MyHeaderView = MyHeaderView.createHeaderView()
            header.setNeedsUpdateConstraints()
            header.updateConstraintsIfNeeded()
            header.frame = CGRectMake(0, 0, CGRectGetWidth(tableView.bounds), CGFloat.max)
            var newFrame = header.frame
            header.setNeedsLayout()
            header.layoutIfNeeded()
            let newSize = header.systemLayoutSizeFittingSize(UILayoutFittingCompressedSize)
            newFrame.size.height = newSize.height
            header.frame = newFrame
            self.tableView.tableHeaderView = header
        }
    }

Solution 4:

This solution resizes the tableHeaderView and avoids infinite loop in the viewDidLayoutSubviews() method I was having with some of the other answers here:

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    if let headerView = tableView.tableHeaderView {
        let height = headerView.systemLayoutSizeFitting(UILayoutFittingCompressedSize).height
        var headerFrame = headerView.frame

        // comparison necessary to avoid infinite loop
        if height != headerFrame.size.height {
            headerFrame.size.height = height
            headerView.frame = headerFrame
            tableView.tableHeaderView = headerView
        }
    }
}

See also this post: https://stackoverflow.com/a/34689293/1245231

Solution 5:

Your solution using systemLayoutSizeFittingSize: works if the header view is just updated once on each view appearance. In my case, the header view updated multiple times to reflect status changes. But systemLayoutSizeFittingSize: always reported the same size. That is, the size corresponding to the first update.

To get systemLayoutSizeFittingSize: to return the correct size after each update I had to first remove the table header view before updating it and re-adding it:

self.listTableView.tableHeaderView = nil;
[self.headerView removeFromSuperview];