UITableViewHeaderView defaulting to hang over cell, not above

Question

I'm using UITableView's viewForHeaderInSection method, but I've decided the that the view would llook nicer with a lowered opacity over the cell by default, where it starts like so:

I'd like it to default like this, as if the user had already scrolled down (note, I want this for all cells, not just the one currently at the top of the view).

I could just add the view as a subview of the cell, except I want it to maintain the functionality where, if the cell is the top cell, the header view stays atop the screen. Maybe the proper way to do this is to not have a headerview, and if a cell is the top cell calculate where the view's origin.y on the cell - although this seems like a potentially expensive way to go about it, it may be the only / best.

Thanks.

PSI'm looking to do this in swift, but objective C would do. Thanks again

Answer 1

Is this what you want?

import UIKit

class ViewController: UITableViewController {
    var data = [[String]]()
    var headerOrigins = [CGPoint]()
    var floatingHeaders = [UIView]()

    override func viewDidLoad() {
        super.viewDidLoad()

        data = [["One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eigth", "Nine", "Ten"], ["One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eigth", "Nine", "Ten"], ["One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eigth", "Nine", "Ten"]]

        tableView.dataSource = self
        tableView.delegate = self

        for i in 0..<data.count {
            headerOrigins += tableView(tableView, cellForRowAtIndexPath: NSIndexPath(forRow: 0, inSection: i)).frame.origin

            let floatingHeader = UIView(frame: CGRectMake(0, headerOrigins[i].y, tableView.frame.size.width, 44))
            floatingHeader.backgroundColor = UIColor.redColor()
            floatingHeader.alpha = 0.5

            let label = UILabel(frame: CGRectMake(100, 10, 100, 30))
            label.text = "Header \(i)"
            floatingHeader.addSubview(label)

            tableView.addSubview(floatingHeader)

            floatingHeaders += floatingHeader
        }

    }

    override func numberOfSectionsInTableView(tableView: UITableView!) -> Int {
        return data.count
    }

    override func tableView(tableView: UITableView!, numberOfRowsInSection section: Int) -> Int {
        return data[section].count
    }

    override func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
        let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as UITableViewCell
        cell.textLabel.text = data[indexPath.section][indexPath.row]

        return cell
    }

    override func scrollViewDidScroll(scrollView: UIScrollView!) {
        var tableTop = tableView.bounds.origin.y + tableView.scrollIndicatorInsets.top

        if tableTop < 0 {
            floatingHeaders[0].frame.origin.y = 0
        } else {
            for i in 0..<data.count {
                if tableTop > headerOrigins[i].y {
                    floatingHeaders[i].frame.origin.y = tableTop
                } else if tableTop < headerOrigins[i].y {
                    floatingHeaders[i].frame.origin.y = headerOrigins[i].y
                }

            var j = i
            while j > 0 {
                if (CGRectGetMaxY(floatingHeaders[j-1].frame) > floatingHeaders[j].frame.origin.y) {
                    floatingHeaders[j-1].frame.origin.y = floatingHeaders[j].frame.origin.y - floatingHeaders[j].frame.size.height
                }
                j--
            }
        }
    }
}