tableView section headers disappear SWIFT

I found an answer in the console output. Use this code in the header function:

func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? 

Do not return your headerCell, or your reusable identifier. Return the reuseIdentifier.contentView. For me it's: return headerCell!.contentView.

Just to add, I was baffled for WAY longer than I should have been as to why I couldn't refer to the contentView of my cell, when I could quite clearly see it was there. My custom class (using UITableViewCell rather than UITableViewHeaderFooterView) would return a fatal error each time. Therefore make sure any custom styling is setup under UITableViewHeaderFooterView class like:

class CustomHeaderCell: UITableViewHeaderFooterView {

You will also need to register the resuableIdentifer like this:

tableView.registerNib(UINib(nibName: "HeaderCell", bundle: nil), forHeaderFooterViewReuseIdentifier: "CellHeader")

Then this bad boy:

    func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {    let headerCell = tableView.dequeueReusableHeaderFooterViewWithIdentifier("CellHeader") as! CustomHeaderCell!    return headerCell!.contentView}

Since I'm not at 50 reputation yet, I can't comment on the previous answer, so I apologize for listing this as another answer.

Returning the ContentView will make the function work but will remove all formatting done to the reuseIdentifier (headerCell)

headerCell.backgroundColor = UIColor.cyanColor()

This will NOT provide a Cyan color to your headerCell

To fix this, just add the ".contentView" to your formatting lines

headerCell.contentView.backgroundColor = UIColor.cyanColor()