multiple view controllers involved, how to send a value back to starting view controller?

Question

I am very new to iOS and overwhelmed with resources I find online. My use case is simple

a.) ViewController parent has label called categoryLabel. A tap on label category opens a new view View 1
b.) View 1, shows all groups. Lets says A, B, C. This will be shown on table
c.) when user click on any group A, B or C, a new view View 2 appears with all categories in that group. For example, user clicks on A and on View 2 user sees categories A1, A2, A3. d.) Now when user clicks on any specific category, how does that goes back to ViewController parent and assigns to categoryLabel?

I do not know what is the best way to approach this design. Any guidance is very much appreciated

You can use the delegate method pattern from iOS. check the link http://stackoverflow.com/questions/6168919/how-do-i-set-up-a-simple-delegate-to-communicate-between-two-view-controllers — user2071152, Nov 20 '14 at 04:56
If you're using a storyboard with segues, then you can use an unwind segue to go back to the first controller, and pass data to it. — rdelmar, Nov 20 '14 at 05:16

Anurag Bhakuni · Accepted Answer · 2014-11-21T05:00:22.527

hope this will help

let take an example , your are going from A -> B and want send some data from B to A , there are many technique to do that but using delegate method and block are nicer way.

delegate way :-

in your B.h file

@protocol yourDelegate <NSObject>

-(void)whichCategoryClicked:(NSString *)categoryName;

@end

@interface B : UIView
@property(nonatomic, assign)id<yourDelegate> delegate;

in your B.m

just call this delegate method after Clicking particular category.

[self.delegate whichCategoryClicked :@"Category_name"];

in your A.h

assign it as delegate and import the above class

@interface A.h : UIViewController<yourDelegate>

and in Implement this method in A.m

first in your viewdidload

{

 B *objB = [[B alloc]init];
    objB.delegate = self;

}

-(void)whichCategoryClicked:(NSString *)categoryName
{
categoryLabel.text = categoryName;
}

What is `DXSemiButtonDelegate`? – daydreamer Nov 20 '14 at 21:46 — daydreamer, Nov 20 '14 at 21:46
srry @daydreamer typo mistake – Anurag Bhakuni Nov 21 '14 at 05:00 — Anurag Bhakuni, Nov 21 '14 at 05:00

score 0 · Answer 2 · answered Nov 20 '14 at 05:03

You can use Local notification for this purpose names as NSNotificationCenter in iOS. Which works as follows:

To send a notification that is from the view on which you are and want to send some value from that view, use below code:

NSDictionary *dict;
[[NSNotificationCenter defaultCenter] postNotificationName:@"NotificationKey" object:nil userInfo:dict];

and now on any of the view controller, you can add observer on viewDidLoad of that class as:

[[NSNotificationCenter defaultCenter] addObserver:self
                                                selector:@selector(methodToCall:)
                                                 name:@"NotificationKey"
                                               object:nil];

Now call method written in above line:

- (void)updateImageFromArray:(NSNotification *)notification {
    // your dict
    NSDictionary *dictUserInfo = [notification userInfo];

}

multiple view controllers involved, how to send a value back to starting view controller?

2 Answers2