Can anyone please tell me how to reload the view.In my program,it contain a tab view controller.There is one item named "A" in the tab.And this "A" item is pointing to a viewController.In that view Controller, it is displaying some datas and I have included UIActionSheet in that. There is one button-Delete in the actionsheet.This delete button is for deleting the particular data.Now my problem is that I need to reload that view so that these deleted data should not be displayed. So anyone please tell me how to reload the page. I have included the following code before
[self presentModalViewController:historyView animated:YES];
[historyView setNeedsDisplay];
but it is showing some error :-
No visible #interface for viewcontroller declares the selector 'setNeedsDisplay'
Please tell me the solution.. :(
UIViewController class doesn't have a method setNeedsDisplay. The UIView class does have this method. So you can write like that:
[historyView.view setNeedsDisplay];
But this method doesn't reload a view. It just marks the receiver’s entire bounds rectangle as needing to be redrawn (from apple documentation iOS Developer Library). So as a result the drawRect method will be called.
To solve your problem you can create your own function like initializeUI in your view controller and then call it when the view is loaded initially (in viewDidLoad method) and for example after deleting the data when you need the view to be updated.
Related
Ok I am trying to refresh the tab content of each of my tabs after a web call has been made, and I have tried soo many different methods to do this that I have lost count. Could someone please tell me how this is possible?
The web call just calls JSON from a server and uses it to update the content of the tabs. For testing purposes I have a button set up inside my settings class. Settings class is a view within the home tab which has a button called refresh. When clicked this takes JSON stored on the device which is different to the one called from the web call on application start up. This saves me having to change the JSON on the server.
I will take you through some of the techniques I have tried and would be grateful if someone could tell me what I am doing wrong.
I tried making an instance of the class and calling the refresh method like this
DashboardVC *db = [[DashboardVC alloc] init];
[db refreshMe];
The refresh method in dashboard class is this
-(void) refreshMe
{
[self loadView];
[self viewDidLoad];
}
However no luck. This method will work if I call it inside the Dashboard class, but wont work if I call it from another class. I think it is become I am instantiating a new class and calling refresh on that. So I dropped that technique and moved onto the next method
This loops through all the tabBars and changes the tabTitles without any issues, so it I know it is definitely looping through the ViewControllers properly.
I also tried every varient of the view methods like ViewDidAppear, viewWillAppear etc, no luck.
I also tried accessing the refreshMe method I made in the dashBoard class through the tabController like this
[[[self.tabBarController viewControllers] objectAtIndex:0] refreshMe];
But again no luck, this just causes my application to crash.
I read through this guide
https://developer.apple.com/library/ios/#documentation/WindowsViews/Conceptual/ViewControllerPGforiOSLegacy/TabBarControllers/TabBarControllers.html
on the apple website but it doesn't seem to cover how to refresh individual tab content.
All I want is to have each individual tab refresh its content after the web call is made, and have spent ages trying to figure this out, but nothing is working.
So would be very grateful if someone could show me what I am doing wrong?
Thanx in advance....
EDIT:
Expand on what I have tried
After discussion with Michael I realised you should never call loadView as against Apple guidelines. So I removed any references to LoadView. I have now placed a method in all the main ViewControllers called RefreshMe which sets up the views, images texts etc in the class. And this method is placed inside the ViewDidLoad. Now I want to be able to call these methods after a web call has taken place, so effectively refreshing the application.
My viewDidLoad now looks like this in all my the main classes.
- (void) viewDidLoad {
[super viewDidLoad];
[self refreshMe];
}
And then the refreshMe method contains the code which sets up the screen.
The JSON data pulled from the web call will set up the content of each of the 5 tabs, so need them all to be refreshed after web call.
I tried looping through the viewControllers and calling viewDidLoad, which should in turn call the refreshMe method which sets up the class, however nothing happens. Code I used was this
NSArray * tabBarViewControllers = [self.tabBarController viewControllers];
for(UIViewController * viewController in tabBarViewControllers)
{
[viewController viewDidLoad];
}
For the time being I have also included
NSLog(#"Method called");
in the viewDidLoad of each class to test if it is being called. However the message is only being printed out when I first load the application or if I re-enter the application. This method should be called after I click the refresh button in the settings screen but it isn't and I have no idea why.
Anyone have any idea why this is not working?
From the question and your comments, it sounds like there are at least two problems:
You're having trouble accessing the view controllers managed by your app's tab bar controller.
You seem to be working against the normal operation of your view controllers.
The first part should be straightforward to sort out. If you have a pointer to an object, you can send messages to that object. If the corresponding method doesn't execute, then either the pointer doesn't point where you think it does or the object doesn't have the method that you think it does. Let's look at your code:
NSArray * tabBarViewControllers = [self.tabBarController viewControllers];
for(UIViewController * viewController in tabBarViewControllers)
{
[viewController viewDidLoad];
}
This code is supposed to call -viewDidLoad on each of the view controllers managed by some tab bar controller. Leaving aside the wisdom of doing that for a moment, we can say that this code should work as expected if self.tabBarController points to the object that you think it does. You don't say where this code exists in your app -- is it part of your app delegate, part of one of the view controllers managed by the tab bar controller in question, or somewhere else? Use the debugger to step through the code. After the first line, does tabBarViewControllers contain an array of view controllers? Is the number of view controllers correct, and are they of the expected types? If the -viewDidLoad methods for your view controllers aren't being called, it's a good bet that the answer is "no," so figure out why self.tabBarController isn't what you think.
Now, it's definitely worth pointing out (as Michael did) that you shouldn't be calling -viewDidLoad in the first place. The view controller will send that method to itself after it has created its view (either loaded it from a .xib/storyboard file or created it programmatically). If you call -viewDidLoad yourself, it'll either run before the view has been created or it'll run a second time, and neither of those is helpful.
Also, it doesn't make much sense to try to "refresh" each view controller's view preemptively. If your app is retrieving some data from a web service (or anywhere else), it should use the resulting data to update its model, i.e. the data objects that the app manages. When a view controller is selected, the tab bar controller will present its view and the view controller's -viewWillAppear method will be called just before the view is displayed. Use that method to grab the data you need from the model and update the view. Doing it this way, you know that:
the view controller's view will have already been created
the data displayed in the view will be up to date, even if one of the other view controllers modified the data
you'll never spend time updating views that the user may never look at
Similarly, if the user can make any changes to the displayed data, you should ensure that you update the model either when the changes are made or else in your view controller's -viewWillDisappear method so that the next view controller will have correct data to work with.
Instead of refreshing your view controllers when updating your tab bar ordering, why not simply refresh your views right before they will appear by implementing your subclassed UIViewController's viewWillAppear: method?
What this means is that each time your view is about to appear, you can update the view for new & updated content.
I have 5 view controllers, which are in a navigation controller hierarchy. When I reach my last view controller, there's a button that lets me go back to the "Home" view controller (named CardWalletViewController) which is a table view controller. Here's the method I have in my last VC (PointsResultsVC)
- (IBAction)homePressed:(id)sender {
NSArray *VCs = [self.navigationController viewControllers];
[self.navigationController popToViewController:[VCs objectAtIndex:0] animated:YES];
}
CardWalletVC's cells is being filled up by values coming from the saved instances of a Card in NSUserDefaults and it works fine.
Now, what I want is to update the value in my CardWalletViewController, which is the points of a card coming from my PointsResultsVC. Note that this points is saved in NSUserDefaults.
Upon the process of trying to update of the value shown in my CardWalletVC, I placed [self.tableView reloadData]; inside -viewDidLoad, -viewWillAppear, and -viewDidAppear of the said class. I tried placing it one by one in each of this methods, yet it doesn't seem to work.
Advice Please.
EDIT: problem solved
This one served as my guide Save data from one tab and reloadData in another tab.
And as I have discovered, -viewDidLoad of a certain class will only be called once, all throughout runtime of app. Whereas -viewWillAppear, it will be called every time the view appears.
So, I just moved the way I am loading the values saved in NSUserDefaults from -viewDidLoad to -viewWillAppear. Also, inside -viewWillAppear I placed the [self.tableView reloadData]. Then there, problem solved.
There's a lot of things that could be going wrong so you'll need to provide more info to narrow it down.
First of all, viewDidLoad will not be called so you can remove it from here. Both viewWillAppear and viewDidAppear will be called, so you only need it one of these 2 methods.
Next, you need to determine what the actual issue is.
1 - is self.tableView a proper reference to the table? Are you properly maintaining the reference?
2 - is the table actually reloading but using the old data, or is it not reloading at all? You can log the willDisplayCell method to see what is going on when the view appears.
With that info, the root cause can be narrowed down to a solvable problem.
As you can guess i am a new programmer and i have trouble getting a simple thing!
I am making an app with multiple view controllers. Each controller have textfields and UIsegmentedControl items. When i am moving from one view controller to the other (uding modal trantition if that matters), the contents of the previous one (textfield entries and segmented control option) reset to their original state. How can i make them keep their previous state?
Thanks in advance.
-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
bViewController *deneme = [segue destinationViewController];
[deneme setPassedValue:label.text];
}
This piece of code will solve your problem, I hope. It saves the label of whatever is inside of it. And you need to add some more code to other classes.
If this code helps you tell me and I can give you the whole code.
To save the application state you can use a model class, following the recommended MVC (model-view-controller) paradigm.
More information here: Retain view state upon reloading
As an alternative you could use the viewWillDisappear: event to save your view state, and then restore it on the viewWillAppear: event.
The viewWillDisappear: event is fired right before the view is going to disappear, and viewWillAppear: is fired before the view is put on the foreground, being ideal to make any changes to the UI.
These events might have already been declared for you in your view controller, but in case they're not check the prototypes here: http://developer.apple.com/library/ios/#documentation/uikit/reference/UIViewController_Class/Reference/Reference.html
You can also use a navigation controller to move from one view to another.
This way, you will push your new view on top of the previous one, and when you go back, the previous view has kept its state.
see this tutorial for more information on storyboard and UINavigationController :
http://www.raywenderlich.com/5138/beginning-storyboards-in-ios-5-part-1
so im having a UIViewController view with a UITableView.
So the UIViewController class name is SelectionScreen.
The UITableView class name is SelectionScreenTable.
Picture:
http://img717.imageshack.us/i/screenshot20100609atpm0.png/
I have declared a UITableView *selectionTable in SelectionScreen class and connected it to the xib file of the SelectionScreen
what the problem is , is that when i click a row in the table,it stays selected as highlighted blue, it calls the didSelectRowAtIndexPath (checked with NSLog) but not pushing a new view which is called(GraphView).
This is the code which i use to call the new controller WHICH WORKS with a normal button
GraphView *aSelectionScreenViewController = [[GraphView alloc]
initWithNibName:#"GraphView"
bundle:nil];
[self presentModalViewController:aSelectionScreenViewController animated: YES];
[aSelectionScreenViewController release];
I searched around and found that I need to set a delegate for the table in the UITableView class itself on the viewload
tableview.delegate = self;
or
self.tableview.delegate = self;
But it was not working. the controller was still not being pushed, and yes i have checked the controller is not nil as i tried it with a simple button.
So i was thinking whether i should set the delegate of the UITableView at the UIViewController instead, so i tried this code
selectionTable.delegate = selectionTable.self;
but obviously it did not work =\, it messed up the whole UITableView and caused all the cells to be its predefined settings.
So does anybody have any idea on how i can get it to work.
It's a bit hard to get the full picture here, but I can try some hints.
The outlets seem to be correctly connected from the screenshot, although Selection Screen Table could probably be called Selection Screen Table Controller and the class name should be SelectionScreenTableController for less confusion.
I think the problem could be that the method presentModalViewController: must be called on an active view controller to work.
From what I can tell you have three view controllers, a SelectionScreenTableController, a GraphViewController, and then there must also be some kind of main controller, probably SelectionScreenController.
The SelectionScreenController is the active view controller, so that must be the one to have sent the presentModalViewController: message.
There are several ways you could solve this. The quick fix would be to make an outlet in SelectionScreenTableController called selectionScreenController and link it to File's Owner in the nib file (assuming your SelectionScreen class is in fact a view controller), then call:
[selectionScreenController
presentModalViewController:aSelectionScreenViewController
animated: YES];
instead in your current listing of didSelectRowAtIndexPath:
Hey guys, i solved it, in the screenshot
http://img717.imageshack.us/i/screenshot20100609atpm0.png/
The SelectionScreenTable controller in the XIB of SelectionScreen, the view outlet was not connected to the XIB in the SelectionScreen XIB, so i guess it wasn't properly configured.
i solved it instead of using
presentModalViewController.
i used an animation to bring in the view instead
More info in the link below
http://www.iphonedevsdk.com/forum/iphone-sdk-development/13427-uiview-slide-transition.html
I shift to my view by
[[self navigationController] popToViewController:controller animated:YES];
In that ViewController, I'm not able to get a notice, that it comes back to front (e.g. by viewWillAppear). I want to reload a table, as soon as the view is visible again.
How do I get a notice, that the view comes back on the screen?
----> solved: See my last comment on Corey's answer
viewWillAppear should be called if you are using a UINavigationController.
Are you sure you have added it correctly to the view hierarchy?
Did you check if viewWillDisappear gets called when it goes offscreen?
Did you try viewDidAppear just to make sure?
Did you spell the method name correctly?
To add:
Is the instance of UINavigationController added directly to the UIWindow instance?
The delegate methods like viewWillappear are sent from UIApplication (I believe). UIApplication only "knows" about viewControllers whose views are either:
Added Directly to UIWindow.
Added to a
UINavigationController/UITabBarCOntroller
that is added directly to UIWindow
(or a chain of these that leads to UIWindow).