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, Mar 13 '12 at 14:53
Can't you use either the NotificationCenter or a protocol to inform your ViewController that the update has ended? — Khal, Mar 13 '12 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, Mar 13 '12 at 15:06
Here is a tutorial on NSNotificationCenter : http://blog.shoguniphicus.com/2011/03/07/objective-c-nsnotification-key-value-observing/ But just for your own record, I would rather use a protocol to inform your ViewController that the update has ended ;) — Khal, Mar 14 '12 at 12:14

score 28 · Answer 1 · edited Aug 09 '19 at 20:27

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 09 '19 at 20:27

buczek

2,011
7
29
40

answered Apr 09 '14 at 13:02

Moaz Saeed

1,006
3
10
23

1

Never ever call lifecycle methods !!! use [self.view setNeedsDisplay] or [self.view setNeedsLayout] for example – Marc Aug 14 '19 at 20:27

score 17 · Answer 2 · answered Jan 13 '17 at 13:29

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 '17 at 13:29

juancazalla

1,050
11
17

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. – Umesh Verma May 14 '20 at 06:43

Rui Peres · Accepted Answer · 2015-07-14T13:03:58.227

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 '15 at 13:03

answered Jun 27 '12 at 14:19

Rui Peres

25,741
9
87
137

I went with this one when I needed it. – Tiago Veloso Jun 27 '12 at 14:56
128

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. – Gogeta70 May 01 '13 at 21:26
1

I want to reload a subview with animation similar to pushing a new view. – swathy krishnan Jun 17 '15 at 11:36

score 8 · Answer 4 · answered Aug 23 '16 at 09:47

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 '16 at 09:47

Patel Jigar

2,141
1
23
30

3

This is not right answer. When u call viewDidLoad for reload view then memory will increase for your application. It's not proper answer.. – Yalamandarao Apr 14 '17 at 09:20
1

still it works for other so please dont make downmark @Singapore – Patel Jigar Sep 07 '17 at 12:50
5

Calling controller lifecycle methods is not at all recommended – Vineet Ashtekar Feb 08 '18 at 13:43
1

so is there any way to reload without increasing memory of the application ? @Singapore – eemrah Apr 28 '18 at 13:13

score 2 · Answer 5 · answered Oct 18 '16 at 02:05

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)

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. — Swifty McSwifterton, Sep 07 '18 at 21:35

score 1 · Answer 6 · answered Jan 27 '17 at 09:31

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().

score 1 · Answer 7 · answered Mar 13 '12 at 14:59

1

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

then just call

[self.view setNeedsDisplay];

answered Mar 13 '12 at 14:59

Shubhank

21,721
8
65
83

2

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. – Tiago Veloso Mar 13 '12 at 20:26

score 0 · Answer 8 · answered Apr 18 '14 at 15:04

0

Reinitialise the view controller

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

answered Apr 18 '14 at 15:04

Muhammad Aamir Ali

20,419
10
66
57

this is old-style. Modern projects with storyboard most likely won't use XIB; use Storyboard instead. – Raptor Jun 06 '14 at 03:06

score -1 · Answer 9 · edited Aug 17 '20 at 11:10

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.

score -6 · Answer 10 · edited Oct 30 '13 at 07:06

-6

You Must use

-(void)viewWillAppear:(BOOL)animated

and set your entries like you want...

edited Oct 30 '13 at 07:06

Hiren

12,720
7
52
72

answered Oct 08 '13 at 13:24

plop

11

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. – Mike Mertsock Oct 08 '13 at 13:52

Reloading a ViewController

10 Answers10

Linked