Swift: Reload a View Controller

Question

I need to refresh a view controller when a certain button is tapped. Simply activating viewDidLoad() does not seem to be working for what I need to do. However, when I leave the view controller and then come back to it, it seems to work perfectly.

How can I refresh/reload a view controller as if I have left it and then come back to it without ever actually leaving it?

Stockman

What exactly are you trying to refresh ? – Harrumph

did you found any solution? – Stinker

This is question is similar to another question I answered. Please look at my response here: updating a view controller with new data – Conditional

Answer 1

Whatever code you are writing in viewDidLoad, Add that in viewWillappear(). This will solve your problem.

Occipital

only if you leave the view controller and come back to it. But if you want to refresh the view controller when a button is tapped, this will not work. – Postulant

Also, this reload data every time the view is shown, even if it not necessary. – Ichinomiya

depends on your navigation hierarchy. If you dismiss a non fullscreen modal, willWillAppear will not be called. – Beeeater

Answer 2

In Swift 5:

self.view.layoutIfNeeded()

Workaday

It's a good answer – Electrocute

Answer 3

You shouldn't call viewDidLoad method manually, Instead if you want to reload any data or any UI, you can use this:

override func viewDidLoad() {
    super.viewDidLoad();

    let myButton = UIButton()

    // When user touch myButton, we're going to call loadData method
    myButton.addTarget(self, action: #selector(self.loadData), forControlEvents: .TouchUpInside)

    // Load the data
    self.loadData();
}

func loadData() {
    // code to load data from network, and refresh the interface
    tableView.reloadData()
}

Whenever you want to reload the data and refresh the interface, you can call self.loadData()

Dumah

How do you do the actual refresh interface part of this? – Immiscible

When you want to reload, call loadData again to get the data from model. In a tableView call reloadData() or in a regular view setNeedsDisplay. – Idealist

// This is where subclasses should create their custom view hierarchy if they aren't using a nib. Should never be called directly. – Increscent

Answer 4

If you are using a navigation controller you can segue again to the current UIViewController and it will be refreshed.

Hit

This is the correct answer to force a refresh of the view controller on a button tap inside that view controller. – Postulant

best answer so far! – Foliage

Answer 5

This might be a little late, but did you try calling loadView()?

Richellericher

public func loadView() // This is where subclasses should create their custom view hierarchy if they aren't using a nib. Should never be called directly. moreHere – Quarterhour

I don't think he is saying to call it directly. He is saying to add code there. – Neutralize

In my case the viewController is disappearing (it's added to tabBar) – Polygynous

Answer 6

View Life Cycle

it will load ViewWillAppear everytime you open the view. above is the link to the picture View Controller Lifecycle.

viewWillAppear()—Called just before the view controller’s content view is added to the app’s view hierarchy. Use this method to trigger any operations that need to occur before the content view is presented onscreen. Despite the name, just because the system calls this method, it does not guarantee that the content view will become visible. The view may be obscured by other views or hidden. This method simply indicates that the content view is about to be added to the app’s view hierarchy.

https://developer.apple.com/library/archive/referencelibrary/GettingStarted/DevelopiOSAppsSwift/WorkWithViewControllers.html

Octavie

Answer 7

If you need to update the canvas by redrawing views after some change, you should call setNeedsDisplay.

Thank you @Vincent from an earlier comment.

Lightship

Answer 8

func clearBackground(){
        loadView()
        view.backgroundColor = .systemBackground
    }

Calling this function for when a button is pressed worked perfectly for me to reload a view.

Annulment

Answer 9

Swift 5.2

The only method I found to work and refresh a view dynamically where the visibility of buttons had changed was:-

viewWillAppear(true)

This may be a bad practice but hopefully somebody will leave a comment.

Delphine