Understanding UISearchBar on Top of UITableView
A Deep Dive into Customizing iOS Search Bar Behavior
In this article, we will delve into the world of customizing iOS search bar behavior, specifically focusing on placing a UISearchBar at the top of a UITableView and hiding it when scrolling down. We’ll explore various approaches to achieve this unique layout.
Background
The traditional way to display a search bar in an iPhone app is by setting its height as the table view header. However, this approach has limitations, such as not adapting to screen size changes or being unable to hide itself when scrolling up. In this article, we will explore alternative methods to create a more dynamic and user-friendly search bar experience.
Setting Up the Environment
Before diving into customizing the search bar behavior, make sure you have a basic understanding of iOS development using Swift or Objective-C. Familiarize yourself with Xcode, the official IDE for Apple’s mobile platforms.
To begin, create a new Single View App project in Xcode and add a UITableView to your view controller:
import UIKit
class ViewController: UIViewController {
let tableView = UITableView()
override func viewDidLoad() {
super.viewDidLoad()
// Add table view to the main layout
view.addSubview(tableView)
// Configure table view layout and data source
tableView.translatesAutoresizingMaskIntoConstraints = false
tableView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
tableView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
tableView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -50).isActive = true
tableView.dataSource = self
tableView.delegate = self
}
}
extension ViewController: UITableViewDataSource, UITableViewDelegate {
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 10
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell()
// Configure table view cell data
cell.textLabel?.text = "Row \(indexPath.row)"
return cell
}
}
Creating the Search Bar Container View
To place the UISearchBar at the top of the UITableView, we’ll create a custom container view that will hold both the search bar and the table view.
Create a new UIView subclass:
import UIKit
class SearchBarContainerView: UIView {
private let search_bar = UISearchBar()
init() {
super.init(frame: .zero)
// Configure search bar layout constraints
self.search_bar.translatesAutoresizingMaskIntoConstraints = false
// Set the search bar's background color to white (optional)
self.search_bar.backgroundColor = .white
// Add the search bar to the view
self.addSubview(searchBar)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
Placing the Search Bar Container View on Top of the Table View
Update the ViewController class:
class ViewController: UIViewController {
// ...
override func viewDidLoad() {
super.viewDidLoad()
// Create and add the search bar container view to the main layout
let search_bar_container_view = SearchBarContainerView()
search_bar_container_view.translatesAutoresizingMaskIntoConstraints = false
// Add constraints to place the search bar on top of the table view
NSLayoutConstraint.activate([
search_bar_container_view.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
search_bar_container_view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
search_bar_container_view.trailingAnchor.constraint(equalTo: view.trailingAnchor)
])
// Configure table view layout and data source
self.tableView.translatesAutoresizingMaskIntoConstraints = false
self.tableView.topAnchor.constraint(equalTo: search_bar_container_view.bottomAnchor, constant: 50).isActive = true
self.tableView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
self.tableView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
self.tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
self.tableView.dataSource = self
self.tableView.delegate = self
}
}
Hiding the Search Bar when Scrolling Down
To hide the search bar when scrolling down, we’ll create a custom UITableViewDelegate extension that will handle this functionality.
extension ViewController: UITableViewDelegate {
func tableView(_ tableView: UITableView, willDisplayHeaderViewHeaderViewType headerType: UITableViewCell.Type) {
if let headerView = tableView.tableHeaderView as? SearchBarContainerView {
// Hide the search bar when scrolling down
if tableView.contentOffset.y > 0 {
headerView.search_barHidden = true
} else {
headerView.search_barHidden = false
}
}
}
}
class SearchBarContainerView: UIView {
@IBInspectable var search_bar_hidden: Bool = false {
didChangeValue()
}
}
Explanation and Conclusion
In this article, we explored alternative methods to create a more dynamic and user-friendly search bar experience by placing the UISearchBar at the top of the UITableView. We created a custom container view that holds both the search bar and the table view, allowing for easier customization and placement.
To hide the search bar when scrolling down, we implemented a custom UITableViewDelegate extension that monitors the scroll position and hides the search bar accordingly. This approach ensures a seamless user experience, adapting to screen size changes and scrolling events.
While this solution may require more setup and configuration, it provides a flexible framework for creating unique layouts and behaviors in iOS apps.
Further Reading:
Last modified on 2023-11-04