Reloading a ViewController

Question

I have a View controller displaying some information (not table views).

I have an update call to a remote server which fills my data base. I would like to completely reload my ViewController after the update call is done.

What should I do?

How do you currently update your data - I am assuming you are using viewDidAppear? — Till
– Till, Commented Mar 13, 2012 at 14:53
Can't you use either the NotificationCenter or a protocol to inform your ViewController that the update has ended? — Khal
– Khal, Commented Mar 13, 2012 at 14:55
@Khal I've never used Notification center, could you point me to a tutorial or guide? @Till I use viewWill/DidAppear as well as loadView and viewDidLoad. — Tiago Veloso
– Tiago Veloso, Commented Mar 13, 2012 at 15:06
Here is a tutorial on NSNotificationCenter : blog.shoguniphicus.com/2011/03/07/… But just for your own record, I would rather use a protocol to inform your ViewController that the update has ended ;) — Khal
– Khal, Commented Mar 14, 2012 at 12:14

buczek · Accepted Answer · 2019-08-09 20:27:55Z

28

If you know your database has been updated and you want to just refresh your ViewController (which was my case). I didn't find another solution but what I did was when my database updated, I called:

[self viewDidLoad];

again, and it worked. Remember if you override other viewWillAppear or loadView then call them too in same order. like.

[self viewDidLoad]; [self viewWillAppear:YES];

I think there should be a more specific solution like refresh button in browser.

edited Aug 9, 2019 at 20:27

buczek

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answered Apr 9, 2014 at 13:02

Moaz Saeed

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1 Comment

Mark Over a year ago

Never ever call lifecycle methods !!! use [self.view setNeedsDisplay] or [self.view setNeedsLayout] for example

juancazalla · Accepted Answer · 2017-01-13 13:29:16Z

17

If you want to reload a ViewController initially loaded from a XIB, you can use the next UIViewController extension:

extension UIViewController {
    func reloadViewFromNib() {
        let parent = view.superview
        view.removeFromSuperview()
        view = nil
        parent?.addSubview(view) // This line causes the view to be reloaded 
    }
}

answered Jan 13, 2017 at 13:29

juancazalla

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1 Comment

Umesh Verma Over a year ago

Hi @juancazalla, I tried the above snippet for refreshing my view controller, so Its again calling viewdidload() method from controller. how to escape this view did load call and refresh my view.

Rui Peres · Accepted Answer · 2015-07-14 13:03:58Z

9

You really don't need to do:

[self.view setNeedsDisplay];

Honestly, I think it's "let's hope for the best" type of solution, in this case. There are several approaches to update your UIViews:

KVO
Notifications
Delegation

Each one has is pros and cons. Depending of what you are updating and what kind of "connection" you have between your business layer (the server connectivity) and the UIViewController, I can recommend one that would suit your needs.

edited Jul 14, 2015 at 13:03

answered Jun 27, 2012 at 14:19

Rui Peres

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3 Comments

Tiago Veloso Over a year ago

I went with this one when I needed it.

Gogeta70 Over a year ago

This answer doesn't really answer the question. You suggest 3 ways to reload the view, but you don't elaborate or even provide links to information on how to implement any of those suggestions.

swathy krishnan Over a year ago

I want to reload a subview with animation similar to pushing a new view.

Patel Jigar · Accepted Answer · 2016-08-23 09:47:26Z

8

Try this, You have to call both methods to reload view, as this one works for me,

-Objective-C

[self viewDidLoad]; 
[self viewWillAppear:YES];

-Swift

self.viewDidLoad()
self.viewWillAppear(true)

answered Aug 23, 2016 at 9:47

Patel Jigar

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4 Comments

Yalamandarao Over a year ago

This is not right answer. When u call viewDidLoad for reload view then memory will increase for your application. It's not proper answer..

Patel Jigar Over a year ago

still it works for other so please dont make downmark @Singapore

Vineet Ashtekar Over a year ago

Calling controller lifecycle methods is not at all recommended

eemmrrkk Over a year ago

so is there any way to reload without increasing memory of the application ? @Singapore

user4410354 · Accepted Answer · 2016-10-18 02:05:32Z

2

Direct to your ViewController again. in my situation [self.view setNeedsDisplay]; and [self viewDidLoad]; [self viewWillAppear:YES];does not work, but the method below worked.

In objective C

UIStoryboard *MyStoryboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil ];
UIViewController *vc = [MyStoryboard instantiateViewControllerWithIdentifier:@"ViewControllerStoryBoardID"];
[self presentViewController:vc animated:YES completion:nil];

Swift:

let secondViewController = self.storyboard!.instantiateViewControllerWithIdentifier("ViewControllerStoryBoardID")   
self.presentViewController(secondViewController, animated: true, completion: nil)

answered Oct 18, 2016 at 2:05

user4410354

2 Comments

Swifty McSwifterton Over a year ago

In my view, the best way to "reload the ViewController" is simply to remove the object from memory and create an entirely new one (as is done above). This also removes viewModels, etc. from memory that were instantiated in the VC (assuming no circular reference issues). Just switching out views doesn't really cut it, and doesn't account for logic running outside the VC that's being refreshed.

user19420200 Over a year ago

'presentViewController(:animated:completion:)' has been renamed to 'present(:animated:completion:)':

swift let secondViewController = self.storyboard!.instantiateViewController(withIdentifier: "ViewControllerStoryBoardID") self.present(secondViewController, animated: true, completion: nil)

Shubhank · Accepted Answer · 2012-03-13 14:59:31Z

1

Update the data ... change button titles..whatever stuff you have to update..

then just call

[self.view setNeedsDisplay];

answered Mar 13, 2012 at 14:59

Shubhank

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1 Comment

Tiago Veloso Over a year ago

I have to reload a couple of entries from the Database. I don't think that redrawing the views is the way to go here.

Vincent · Accepted Answer · 2017-01-27 09:31:16Z

1

It is not advised to call ViewDidLoad or ViewWillAppear by yourself.

In the ViewDidLoad include a loadData() function to prepare the data. This is executed in the initial run.

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().

answered Jan 27, 2017 at 9:31

Vincent

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Comments

Muhammad Aamir Ali · Accepted Answer · 2014-04-18 15:04:41Z

0

Reinitialise the view controller

YourViewController *vc = [[YourViewController alloc] initWithNibName:@"YourViewControllerIpad" bundle:nil];
[self.navigationController vc animated:NO];

answered Apr 18, 2014 at 15:04

Muhammad Aamir Ali

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1 Comment

Raptor Over a year ago

this is old-style. Modern projects with storyboard most likely won't use XIB; use Storyboard instead.

iknow · Accepted Answer · 2020-08-17 11:10:19Z

-1

For UIViewController just load your view again -

func rightButtonAction() {
        if isEditProfile {
           print("Submit Clicked, Call Update profile API")
            isEditProfile = false
            self.viewWillAppear(true)
        } else {
            print("Edit Clicked, Call Edit profile API")
            isEditProfile = true
            self.viewWillAppear(true)
        }
    }

I am loading my view controller on profile edit and view profile. According to the Bool value isEditProfile updating the view in viewWillAppear method.

edited Aug 17, 2020 at 11:10

iknow

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answered Aug 17, 2020 at 10:42

Shashi Tiwari

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Comments

Hiren · Accepted Answer · 2013-10-30 07:06:26Z

-6

You Must use

-(void)viewWillAppear:(BOOL)animated

and set your entries like you want...

edited Oct 30, 2013 at 7:06

Hiren

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answered Oct 8, 2013 at 13:24

plop

11

1 Comment

Mike Mertsock Over a year ago

This might be a valid hint for for when to send the request to a web service to load data, but it doesn't answer how to handle the web service response asynchronously to update the view.

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