Having trouble with CollectionView in Xcode - display's black screen

Question

Basically I've been writing iOS apps for about 3 days (after reading a book to get the basic knowledge of design patterns and frameworks etc) and 1 entire day has been spent on this. I cannot get my CollectionView to display. I've got a storyboard that starts with a TabBarView and the two tabs (one is a TableView and the other is just a UIView) work, but the third tab (UICollectionView) just displays a black screen even after setting up. How I set it up:

1) dragged a ViewController to the storyboard

2) made a relationship segue between my UITabBarController to the new ViewController

3) dragged a UICollectionView to the new ViewController

4) dragged 4 UICollectionViewCell's to the CollectionView

5) dragged 4 UILabels into said CollectionViewCell's

6) made a connection between the new CollectionView's delegate & data source and the header file of my CollectionView class (this might be where I went wrong, I did not make the connection to my ViewController.h class as I used this one for my UITableView and thought a new class was necessary)

7) declared the following methods in my CollectionView.m file

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
//Populates each cell using the data given (no data in this case).
//Should return a CollectionViewCell.
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];

return cell;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    //Gets the number of cells in each section.
    //Should return an integer value.
    return 2;
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    //Tells the collection view the number of sections it should have.
    //Should return an integer value.
    return 4;
}

I get the feeling there is something I missed out, as this logic makes sense to me as a programmer but, having such little experience in Xcode, maybe I forgot to link up this class to my CollectionView or something. Does anybody know where I went wrong?

BTW in case you're wondering, I'm using this CollectionView more of a navigation technique than to display wonderful images or anything, I am going to populate them with generic images later when they actually show up in the emulator. thanks

Answer 1

It is not displaying anything because default color of label is black, you'll have to change the color of text to any light color to see text over cell.

Now, 

->Add a new file which should be subclass of UICollectionViewCell, Ctrl+drag from label to this class.(for eg I took mainViewCell)and label property name I took labelText

->Declare reuseIdentifier for cell from Attribute Inspector,(mainCell, I took)

->Import cellClass to your UIViewController Class,

->Using this method to display any text

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    mainViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"mainCell" forIndexPath:indexPath];
    cell.labelText.text = @"What-ever-you-want-display";
    return cell;
}

hope this would help...

Answer 2

Did you tell your view controller(the one that contains the collection view) to use UICollectionViewDelegateFlowLayout? For example,

@interface RootViewController () <UICollectionViewDelegateFlowLayout, UICollectionViewDataSource>

Also, have you set the reuse identifier for your cell? In Interface Builder set this in the attributes inspector. Then go to the cellForItemAtIndexPath: method and change this line to use your identifier. UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"MyCell" forIndexPath:indexPath];

Check out UICollectionViewDelegateFlowLayout in the documentation for methods used to size cells and set margins and spacing.

Answer 3

The step 6) might be inadequate. Have you ctrl-dragged the collectionView to the controller icon beneath the main view directly? You would have been prompted in a black dialog box for connecting dataSource and delegate. The connections are made in XCode this way. Alternatively you could explicitly set the dataSource as self in the controller implementation.

Answer 4

Remove registerClass code from the default view controller code snippet

[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:reuseIdentifier];