How to implement UISearchController in UITableView - Swift

Question

I am a newbie to Swift and I am trying to add search functionality to my UITableView which is in a UIViewController class. I googled a lot and found that UISearchDisplayController has been deprecated and replaced by UISearchController. When I tried to search for tutorials I did not find any specifically for UITableView. Some of them were for implementing in UITableViewController. So here are my questions:

1. Can we implement UISearchController in a UITableView that is in a UIViewController class? (I guess we can)

2. If we can, please convert these line of codes written in Objective-C. Or if there are some really good tutorials please let me know.

   @property (strong, nonatomic) UISearchController *searchController;
   
   UITableViewController *searchResultsController = [[UITableViewController alloc] init];
   
   // Init UISearchController with the search results controller
    self.searchController = [[UISearchController alloc] initWithSearchResultsController:searchResultsController];
   
   // Link the search controller
   self.searchController.searchResultsUpdater = self;
   

Source

EDIT : I am trying to assign the search results updater in as

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, UISearchResultsUpdating {

    override func viewDidLoad() {

       super.viewDidLoad()
       self.view.backgroundColor = UIColor.blackColor() 
       self.addTableViewWithSection() 
       self.searchResultsController = UITableViewController()           
       var controller = UISearchController(searchResultsController: nil)            
       controller.searchResultsUpdater = self           
       controller.dimsBackgroundDuringPresentation = false   
    }
}

*However on the line controller.searchResultsUpdater = self i get the eroor as Cannot assign a value of typ "ViewController" to a value of type "UISearchResultsUpdating?" .. So i really doubt if i can use UISearchController in UIViewController type class.

Answer 1

Yes, the way search works has been radically changed for what I consider to be a better system. The new system is much better and straight to the point for most simple implementations. Using it is pretty straightforward.

First, make your class comply with the UISearchResultsUpdating protocol.

class MyTableViewController: UITableViewController, UISearchResultsUpdating {}

Add it the search controller property:

class MyTableViewController: UTableViewController, UISearchResultsUpdating {
    let searchController = UISearchController(searchResultsController: nil)
}

Add the search bar in viewDidLoad:

override func viewDidLoad() {
    super.viewDidLoad()

    searchController.searchResultsUpdater = self
    searchController.hidesNavigationBarDuringPresentation = false
    searchController.dimsBackgroundDuringPresentation = false
    searchController.searchBar.sizeToFit()
    self.tableView.tableHeaderView = searchController.searchBar
}

And finally, implement the updateSearchResults:for method that comes from the UISearchResultsUpdating protocol:

func updateSearchResults(for searchController: UISearchController) {

}

Your implementation of this method will of course depend on where you are searching the data from. It will update your current table view with the contents of your search as you type them. Make sure you update your data source and reload the table view in the updateSearchResultsForSearchController method. Again, it updates as you type so make sure that if your data to search in is big or if you are searching from the internet, add some concurrency in this method.

If you want to use a different controller to populate your search results with, you can pass that VC when initialising the searchController property.

EDIT: I have reread your question and it looks like I forgot to add something important.

UITableViewController has a member called tableView. You can grab the controller's table view , but to populate your UITableView, you don't need to touch it. You can't use the SearchController logic directly with UITableView. You gotta work with the controller to get it there. Use the UITableViewController delegate and data source methods to get your table UI updated with your search results.

Please read on using UITableViewController, UITableViewDelegate, and UITableViewDataSource so you can understand how to get your search results there.

Answer 2

In case of anyone, who is freaking around like me..this code might help

class ViewController: UIViewController , UITableViewDataSource, UITableViewDelegate,UISearchResultsUpdating {

    @IBOutlet weak var tblView: UITableView!

    var tabledata = ["lucques","chickendijon","godaddy","amazon","chris","ambata","bankofamerica","abelcine","AUTO + TRANSPORTATION","BILLS + UTILITIES","FOOD + DINING","HEALTH","AutoCare", "Auto Payment" , "Gas+Fuel","Electric Bill", "Internet/Television","Fast Foodd", "Gorceries" , "Restaurants","Gym Membership", "Health Insurance","auto","note-bullet","knife","heart"]

    var filteredTableData = [String]()
    var resultSearchController = UISearchController()

    override func viewDidLoad() {
        super.viewDidLoad()
        tblView.delegate = self
        tblView.dataSource = self
        self.resultSearchController = ({
            let controller = UISearchController(searchResultsController: nil)
            controller.searchResultsUpdater = self
            controller.dimsBackgroundDuringPresentation = false
            controller.searchBar.sizeToFit()
            controller.searchBar.barStyle = UIBarStyle.Black
            controller.searchBar.barTintColor = UIColor.whiteColor()
            controller.searchBar.backgroundColor = UIColor.clearColor()
            self.tblView.tableHeaderView = controller.searchBar
            return controller
        })()
        self.tblView.reloadData()
    }

     func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return 1
    }
    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if self.resultSearchController.active {
           return self.filteredTableData.count
        }else{
            return self.tabledata.count
       }
    }
     func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        var section = indexPath.section
        var row = indexPath.row
        let cell: UITableViewCell = UITableViewCell(style: UITableViewCellStyle.Default, reuseIdentifier:"addCategoryCell")
        cell.selectionStyle =  UITableViewCellSelectionStyle.None
        cell.backgroundColor = UIColor.clearColor()
        cell.contentView.backgroundColor = UIColor.clearColor()
        cell.textLabel?.textAlignment = NSTextAlignment.Left
        cell.textLabel?.textColor = UIColor.blackColor()
        cell.textLabel?.font = UIFont.systemFontOfSize(14.0)

        if self.resultSearchController.active {
              cell.textLabel?.text = filteredTableData[indexPath.row]
        } else {
                 cell.textLabel?.text = tabledata[indexPath.row]
        }
        return cell
    }

    func updateSearchResultsForSearchController(searchController: UISearchController) {
        filteredTableData.removeAll(keepCapacity: false)
        let searchPredicate = NSPredicate(format: "SELF CONTAINS[c] %@", searchController.searchBar.text)
        let array = (tabledata as NSArray).filteredArrayUsingPredicate(searchPredicate)
        filteredTableData = array as! [String]
        self.tblView.reloadData()

    }
}

Answer 3

For those looking for a bit more context on all the aspects of implementing this, here's a tutorial on how to implement UISearchController

In addition to the above answer by Andy Ibanez, you also need to add code to your UITableViewDataSource methods to show the newly filtered results in the tableview.

Also, don't forget to call tableView.reloadData() in your updateSearchResults method - the UISearchController does not automatically tell the tableView to reload its data.