Peek and Pop on UITableView cells fails with UISearchController

Question

Peek and Pop is working with a UISearchController. However, Peek and Pop stops working once you start searching the table using updateSearchResults.

Answer 1

First, in your MainTableViewController.viewDidLoad() you need to also register your resultsTableController.tableView, since that is a separate view that will receive peek/pop information:

if traitCollection.forceTouchCapability == .available {
    previewingContext = registerForPreviewing(with: self, sourceView: tableView)
    if let resultVC = searchController.searchResultsController as? ResultsTableController {
        resultVC.registerForPreviewing(with: self, sourceView: resultVC.tableView)
    }
}

When testing this solution, I noticed a strange problem, that the first row in the result set wasn't peekable, and blank rows in the result set WERE peekable. So, the second fix in previewingContext(_:viewControllerForLocation:):

func previewingContext(_ previewingContext: UIViewControllerPreviewing, viewControllerForLocation location: CGPoint) -> UIViewController? {
    guard let tableView = previewingContext.sourceView as? UITableView,
        let indexPath = tableView.indexPathForRow(at: location),

In your original code, it was using the tableView property on the MainTableViewController instead of the tableView that was the sourceView for the interaction.

Now, this works when you're searching, and when you're not. However, when you've entered the search, but haven't entered any search text yet, the UISearchController is active, but the UITableView is the one from MainTableViewController, and you cannot register a view as a source view twice. So, we have a little more work to do:

// local property to store the result from registerForPreviewing(with:sourceView:)
var previewingContext: UIViewControllerPreviewing?

func didPresentSearchController(_ searchController: UISearchController) {
    if let context = previewingContext {
        unregisterForPreviewing(withContext: context)
        previewingContext = searchController.registerForPreviewing(with: self, sourceView: tableView)
    }
}

func didDismissSearchController(_ searchController: UISearchController) {
    if let context = previewingContext {
        searchController.unregisterForPreviewing(withContext: context)
        previewingContext = registerForPreviewing(with: self, sourceView: tableView)
    }
}

Basically, when the UISearchController is presented, we unregister MainTableViewController and register the search controller. When it is dismissed, we do the reverse.

With these changes, peek and pop work in all three states.