How to prevent the keyboard from closing when typing in a UITextField embedded in a UICollectionView header cell using Swift?

Question

I want to search a UICollectionView using a custom UITextfield embedded in a UICollectionView header cell. I have a delegate method that passes inputed text to the main view controller, however, every letter you input in the textfield causes the keyboard to resign because the collection view is reloaded.

// SearchHeaderView

protocol SearchHeaderViewDelegate: AnyObject {
    func search(with searchString: String)
}

class SearchHeaderView: UICollectionViewCell, UITextFieldDelegate {

    weak var delegate: SearchHeaderViewDelegate?

    lazy var searchContainerView: InputContainerView = {
        return InputContainerView(image: UIImage(named: "96_search_line")!,
                                  textField: searchTextField)
    }()

    let searchTextField = CustomTextField(placeholder: "Search",
                                          keyboard: .default,
                                          autoCapitalization: .words)

    override init(frame: CGRect) {
        super.init(frame: .zero)
        searchTextField.delegate = self
    }

    func textFieldDidChangeSelection(_ textField: UITextField) {
        if (searchTextField.text?.count)! != 0 {
            delegate?.search(with: textField.text!)
        }
    }
}

// ViewController

collectionView.register(SearchHeaderView.self, forSupplementaryViewOfKind:
                                UICollectionView.elementKindSectionHeader, withReuseIdentifier: "headerId")

func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
    let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier:
                                                                    "headerId", for: indexPath) as! SearchHeaderView
    header.delegate = self
    return header
}

extension ViewController: SearchHeaderViewDelegate {
    func search(with searchString: String) {
        print("TESTING: Search containing \(searchString)")
        // search function...
        collectionView.reloadData() // causes the keyboard to close
    }
}

Paul Ancajima · Answer

So, it sounds like its performing the search function with every key press. Is there a way for you to add a debounce to the textfield? You can try set the delay for a long time.

Something like this

import Combine

var cancellables = Set()

override func viewDidLoad() {
  super.viewDidLoad()
  applyCombineSearch()
}

//Initialise the publisher and subscriber for search
func applyCombineSearch() {
  let publisher = NotificationCenter.default.publisher(for: searchTextField.textDidChangeNotification, object: viewController.collectionView.searchTextField)
  publisher
    .map {
      ($0.object as! CustomTextField).text
  }
  .debounce(for: .seconds(20), scheduler: RunLoop.main)
  .sink(receiveValue: { (value) in
    DispatchQueue.global(qos: .userInteractive).async { [weak self] in
      // Perform search
      DispatchQueue.main.async {
        collectionView.reloadData()
      }
    }
  })
  .store(in: &cancellables)
}

How to prevent the keyboard from closing when typing in a UITextField embedded in a UICollectionView header cell using Swift?

1 Answers