How to use pull to refresh in Swift?

Question

I am building an RSS reader using swift and need to implement pull to reload functionality.

Here is how i am trying to do it.

class FirstViewController: UIViewController,
    UITableViewDelegate, UITableViewDataSource {

   @IBOutlet var refresh: UIScreenEdgePanGestureRecognizer
   @IBOutlet var newsCollect: UITableView

   var activityIndicator:UIActivityIndicatorView? = nil

   override func viewDidLoad() {
       super.viewDidLoad()
       self.newsCollect.scrollEnabled = true
      // Do any additional setup after loading the view, typically from a nib.

      if nCollect.news.count <= 2{
          self.collectNews()
       }
      else{
          self.removeActivityIndicator()
       }
      view.addGestureRecognizer(refresh)
   }



@IBAction func reload(sender: UIScreenEdgePanGestureRecognizer) {
    nCollect.news = News[]()
    return newsCollect.reloadData()
}

I am getting :

Property 'self.refresh' not initialized at super.init call

Please help me to understand the behaviour of Gesture recognisers. A working sample code will be a great help.

Thanks.

Answer 1

In Swift use this,

If you wants to have pull to refresh in WebView,

So try this code:

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

func addPullToRefreshToWebView(){
    var refreshController:UIRefreshControl = UIRefreshControl()

    refreshController.bounds = CGRectMake(0, 50, refreshController.bounds.size.width, refreshController.bounds.size.height) // Change position of refresh view
    refreshController.addTarget(self, action: Selector("refreshWebView:"), forControlEvents: UIControlEvents.ValueChanged)
    refreshController.attributedTitle = NSAttributedString(string: "Pull down to refresh...")
    YourWebView.scrollView.addSubview(refreshController)

}

func refreshWebView(refresh:UIRefreshControl){
    YourWebView.reload()
    refresh.endRefreshing()
}

Answer 2

Anhil's answer helped me a lot.

However, after experimenting further I noticed that the solution suggested sometimes causes a not-so-pretty UI glitch.

Instead, going for this approach* did the trick for me.

*Swift 2.1

//Create an instance of a UITableViewController. This will host your UITableView.
private let tableViewController = UITableViewController()

//Add tableViewController as a childViewController and set its tableView property to your UITableView.
self.addChildViewController(self.tableViewController)
self.tableViewController.tableView = self.tableView
self.refreshControl.addTarget(self, action: "refreshData:", forControlEvents: .ValueChanged)
self.tableViewController.refreshControl = self.refreshControl

Answer 3

iOS 10 - Swift 3 (Also applicable for iOS 11 - Swift 4)

I would like to mention a PRETTY COOL feature that has been included since iOS 10, which is:

For now, UIRefreshControl is directly supported in each of UICollectionView, UITableView and UIScrollView!

Each one of these views have refreshControl instance property, which means that there is no longer a need to add it as a subview in your scroll view, all you have to do is:

@IBOutlet weak var collectionView: UICollectionView!

override func viewDidLoad() {
    super.viewDidLoad()

    let refreshControl = UIRefreshControl()
    refreshControl.addTarget(self, action: #selector(doSomething), for: .valueChanged)

    // this is the replacement of implementing: "collectionView.addSubview(refreshControl)"
    collectionView.refreshControl = refreshControl
}

func doSomething(refreshControl: UIRefreshControl) {
    print("Hello World!")

    // somewhere in your code you might need to call:
    refreshControl.endRefreshing()
}

Personally, I find it more natural to treat it as a property for scroll view more than add it as a subview, especially because the only appropriate view to be as a superview for a UIRefreshControl is a scrollview, i.e the functionality of using UIRefreshControl is only useful when working with a scroll view; That's why this approach should be more obvious to setup the refresh control view.

However, you still have the option of using the addSubview based on the iOS version:

if #available(iOS 10.0, *) {
  collectionView.refreshControl = refreshControl
} else {
  collectionView.addSubview(refreshControl)
}

Answer 4

For the pull to refresh i am using

DGElasticPullToRefresh

https://github.com/gontovnik/DGElasticPullToRefresh

Installation

pod 'DGElasticPullToRefresh'

import DGElasticPullToRefresh

and put this function into your swift file and call this funtion from your

override func viewWillAppear(_ animated: Bool)

     func Refresher() {
      let loadingView = DGElasticPullToRefreshLoadingViewCircle()
      loadingView.tintColor = UIColor(red: 255.0/255.0, green: 255.0/255.0, blue: 255.0/255.0, alpha: 1.0)
      self.table.dg_addPullToRefreshWithActionHandler({ [weak self] () -> Void in

          //Completion block you can perfrom your code here.

           print("Stack Overflow")

           self?.table.dg_stopLoading()
           }, loadingView: loadingView)
      self.table.dg_setPullToRefreshFillColor(UIColor(red: 255.0/255.0, green: 57.0/255.0, blue: 66.0/255.0, alpha: 1))
      self.table.dg_setPullToRefreshBackgroundColor(self.table.backgroundColor!)
 }

And dont forget to remove reference while view will get dissapear

to remove pull to refresh put this code in to your

override func viewDidDisappear(_ animated: Bool)

override func viewDidDisappear(_ animated: Bool) {
      table.dg_removePullToRefresh()

 }

And it will looks like

Happy coding :)

Answer 5

Others Answers Are Correct But for More Detail check this Post Pull to Refresh

Enable refreshing in Storyboard

When you’re working with a UITableViewController, the solution is fairly simple: First, Select the table view controller in your storyboard, open the attributes inspector, and enable refreshing:

A UITableViewController comes outfitted with a reference to a UIRefreshControl out of the box. You simply need to wire up a few things to initiate and complete the refresh when the user pulls down.

Override viewDidLoad()

In your override of viewDidLoad(), add a target to handle the refresh as follows:

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    self.refreshControl?.addTarget(self, action: "handleRefresh:", forControlEvents: UIControlEvents.ValueChanged)
}

1. Since I’ve specified “handleRefresh:” (note the colon!) as the action argument, I need to define a function in this UITableViewController class with the same name. Additionally, the function should take one argument
2. We’d like this action to be called for the UIControlEvent called ValueChanged
3. Don't forget to call refreshControl.endRefreshing()

For more information Please go to mention Link and all credit goes to that post

Answer 6

A Solution with storyboard and swift...

1.) Open your .storyboard file, select a TableViewController in your storyboard and "Enable" the Table View Controller - Refreshing feature in the Utilities.

2.) Open the associated UITableViewController-Class and add the following line into the viewDidLoad-Method.

self.refreshControl?.addTarget(self, action: "refresh:", forControlEvents: UIControlEvents.ValueChanged)

OR in Swift 2.2:

self.refreshControl?.addTarget(self, action: #selector(TestTableViewController.refresh(_:)), forControlEvents: UIControlEvents.ValueChanged)

3.) Add the following Method above the viewDidLoad-Method

func refresh(sender:AnyObject)
{
    // Updating your data here...

    self.tableView.reloadData()
    self.refreshControl?.endRefreshing()
}