UICollectionView inside of a Container View - Refresh on button click

Question

Problem

As illustrated, I have a container view (B) which resides inside of a view with other controls on it (A). The container view (B) holds a collection view, which I would like to update whenever a button is pressed on view (A).

I have gone through the UICollectionView Basics but feel I must be missing something. My natural response when wanting to communicate between UIViewControllers is to go off and build something based on either a callback or other delegate mechanism. Before I reinvent the wheel, any thoughts?

Currently when I click the buttons in the view, my collection data is updated and I call setNeedsDisplay and reloadData on the collection view (accessed via the childViewControllers property). I've tried calling setNeedsDisplay on the container view itself as well (no joy).

BTW - I have reviewed similar SO questions, which do not provide a matching use-case but do seem to indicate a lack of insight on this particular type of issue (if I've missed a great answer please let me know):

A, B, C, D

Solution

Please note that I've shared my solution below but additional answers are still welcome (especially if it's a better way)

Answer 1

Solution

Since my search of the community showed marginal information on this topic, I am sharing my solution. I added a callback function on my data controller. Then upon closer inspection of How to tell UICollectionView about your content, I realized that I could simplly toggle the data source as indicated below (so I did a combination of both):

Please note the multiple options mentioned on how to get a UICollectionView to update itself.

Details

In my .h file for my data controller

//above @interface

typedef void (^CallbackBlock)();

//within @interface

@property (strong, nonatomic) CallbackBlock onDataUpdated;

//within my data controller method where data was changed

[DataManager sharedManager].onDataUpdated(); //singleton, i know...

//alternative to above singleton

__weak DataManager* weakSelf = [[DataManager alloc]init];
weakSelf.onDataUpdated();

//In my UIViewController (B) subclass

@property (strong,nonatomic)DataManager* controller;

//In my view did load of UIVC (B)

self.controller = [DataManager sharedManager];

__weak ProgressViewController* weakSelf = self;

self.controller.onDataUpdated = ^(){
    //perform my action
    [weakSelf setData:nil]; //remove existing data
    [weakSelf setData:[self getSomeData]]; //get some new data
    [[weakSelf progressCollectionView]reloadData]; 
    [[weakSelf progressCollectionView] setNeedsDisplay];
};

End result:

1. UIVC (A) receives button click
2. Data Manager class fires the data updated event at end of method execution for step 1
3. UIVC (B) instantly reloads the data without refreshing other subviews of UIVC (A)