IOS, UICollectionview - ios

Question

New to IOS and objective C and been doing several tutorials, with adding buttons, textfields etc. Been looking alot on stackoverflow, which has been very helpful :) Now I am trying to create a collectionview within a frame and then put a button below it. I can get a button to show up, and the top half of the screen where I have defined the collection to appear turns black, while the rest goes white, as intended. Currently the collection should come up with a label telling me the cell number, so very basic. Not sure if I'm setting up my views wrong, or if there is something wrong with my CellViews.
I have created a mainView controller, where I have defined my button and collection view, like this:
MainViewController.h:
#interface MainViewController : UIViewController <UICollectionViewDataSource, UICollectionViewDelegateFlowLayout>
#property(nonatomic, strong) IBOutlet UICollectionView *collectionView;
#property(nonatomic, strong) IBOutlet UIButton *diaryButton;
- (id)init;
My .m looks like this:
#implementation MainViewController
#synthesize collectionView;
#synthesize diaryButton;
- (id) init {
self = [super init];
if (self) {
CGRect buttonFrame = CGRectMake(10, 250, 70, 30);
diaryButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[diaryButton setFrame:buttonFrame];
[diaryButton setTitle:#"Diary" forState:UIControlStateNormal];
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
layout.itemSize = CGSizeMake(64.0, 64.0);
layout.minimumInteritemSpacing = 4;
layout.minimumLineSpacing = 4;
layout.scrollDirection = UICollectionViewScrollPositionCenteredVertically;
layout.sectionInset = UIEdgeInsetsMake(2.0, 2.0, 2.0, 2.0);
CGRect collectionFrame = CGRectMake(0, 0, 320, 200);
collectionView = [[UICollectionView alloc] initWithFrame:collectionFrame collectionViewLayout:layout];
[self.view addSubview:collectionView];
[self.view addSubview:diaryButton];
//[self.view setBackgroundColor:[UIColor blueColor]];
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:#"ID"];
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return 30;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"ID" forIndexPath:indexPath];
UILabel *label = [[UILabel alloc] initWithFrame:cell.bounds];
label.textAlignment = NSTextAlignmentCenter;
label.text = [NSString stringWithFormat:#"%d", indexPath.row];
[cell.contentView addSubview:label];
return cell;
}
/////////////////////////////////////////////////////////////////////////////////
// collection view delegate methods ////////////////////////////////////////
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"cell #%d was selected", indexPath.row);
}
My appdelegate looks like this:
#synthesize mainVC;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.mainVC = [[MainViewController alloc] init];
[self.window addSubview:mainVC.view];
//self.window.rootViewController = mainVC;
// Override point for customization after application launch.
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
return YES;
}
Any help will be greatly appreciated.

Answer 1

I don't know exactly why your collection isn't showing anything, but you're missing the numberOfSectionsInCollectionView: method from the UICollectionViewDataSource. The collection view might be assuming that the number of sections is 0.
http://developer.apple.com/library/ios/#documentation/uikit/reference/UICollectionViewDataSource_protocol/Reference/Reference.html
Also, did you set the datasource and delegate to self for your UICollectionView?