Is it possible to force rebuild previous view of a Navigation Controller - objective-c

Question

I have a table view in my previous view which is get data from an array in my app. I have a view to update data which is push on cell select. Once data is updated in the view i call
[self.navigationController popViewControllerAnimated:YES];
to go back to previous view. But the label get stacked with old and new data I don't know why... If I go one view back and come back again to the tableview everything is fine only new data is shown..
So I guess I have to rebuild view to avoid the problem. Is this possible ?

Answer 1

Your question initially asked about rebuilding a controller, so here's the answer to that:
I'm assuming that your have a navigation stack like this:
An instance of FirstController
An instance of SecondController
An instance of ThirdController
A thing happens in your third controller, and you now want the stack to look like this:
An instance of FirstController
A new instance of SecondController
The first thing to do is to define a delegate protocol for ThirdController, in your header file like this:
#protocol ThirdControllerDelegate;
#class ThirdController : UIViewController
#property (nonatomic, weak) id<ThirdControllerDelegate> delegate;
... your existing stuff ...
#end
#protocol ThirdControllerDelegate <NSObject>
- (void)thirdControllerDidDoTheThing:(ThirdController *)thirdController;
#end
Instead of having the ThirdController pop itself, it should tell its delegate that the thing happened, like so:
[self.delegate thirdControllerDidDoTheThing:self];
You'll also want to define a delegate protocol for SecondController, in the same way, and you'll want to specify that SecondController can act as a delegate for a ThirdController:
#import "ThirdController.h"
#protocol SecondControllerDelegate;
#class SecondController : UIViewController <ThirdControllerDelegate>
#property (nonatomic, weak) id<SecondControllerDelegate> delegate;
... your existing stuff ...
#end
#protocol SecondControllerDelegate <NSObject>
- (void)secondControllerDidDoTheThing:(SecondController *)secondController;
#end
Notice the extra bit in there where we put <ThirdControllerDelegate> after the #class line.
Now we find the part of the SecondController that shows the ThirdController, and have it set the controller's delegate first:
- (void)showThirdControllerAnimated:(BOOL)animated
{
ThirdController *thirdController = [[ThirdController alloc] init];
thirdController.delegate = self;
[self.navigationController pushViewController:thirdController animated:animated];
}
When the SecondController gets the message from the ThirdController, it should pass it on to its delegate, like this:
- (void)thirdControllerDidDoTheThing:(ThirdController *)thirdController
{
[self.delegate secondControllerDidDoTheThing:self];
}
Finally we modify FirstController so that it can act as the delegate to the SecondController:
#import "SecondController."
#class FirstController : UIViewController <SecondControllerDelegate>
When we show the SecondController, we make the FirstController its delegate:
- (void)showSecondControllerAnimated:(BOOL)animated
{
SecondController *secondController = [[SecondController alloc] init];
secondController.delegate = self;
[self.navigationController pushViewController:secondController animated:animated];
}
Finally we implement the SecondController's delegate method to pop to the first controller, then show a new secondController.
- (void)secondControllerDidDoTheThing:(SecondController *)secondController
{
[self.navigationController popToViewController:self animated:NO];
[self showSecondControllerAnimated:NO];
}
Done.
You've since altered your question; in the case you now describe you can follow the steps above to make the SecondController the delegate of the ThirdController, but then inside thirdControllerDidDoTheThing you just reload the data of your SecondController's view; if it's a UITableView or UICollectionView you'd do that with the reloadData method.

Answer 2

you should refresh your table view every time it is going to be shown; otherwise, the old data would be cached.
In the controller that controls the table view:
- (void)viewWillAppear {
[tableView reloadData];
}