By kusumoto_teruya


2014-06-18 15:01:29 8 Comments

I added UICollectionView by code.
Now, the app crash with message: UICollectionView must be initialized with a non-nil layout parameter.
Do you have any idea to fix it?
CollectionCell is custom class of UICollectionViewCell.

@property (nonatomic, strong) UICollectionView* collectionView;

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.collectionView = [[UICollectionView alloc]init];
    [self.collectionView registerClass:[CollectionCell class] forCellWithReuseIdentifier:@"cell"];
    UICollectionViewFlowLayout* flowLayout = [[UICollectionViewFlowLayout alloc]init];
    flowLayout.itemSize = CGSizeMake(100, 100);
    [flowLayout setScrollDirection:UICollectionViewScrollDirectionHorizontal];
    [self.collectionView setCollectionViewLayout:flowLayout];

    self.collectionView.frame = CGRectMake(0, 60, 320, 500);
    self.collectionView.backgroundColor = [UIColor whiteColor];
    self.collectionView.delegate = self;
    self.collectionView.dataSource = self;
    [self.view addSubview:self.eventCollection];
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 1;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return 20;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    CollectionCell* cell = [self.eventCollection dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
    cell.label.text = [NSString stringWithFormat:@"%d", indexPath.item];
    return cell;
}

4 comments

@ravron 2014-06-18 15:45:30

The crash is telling you pretty explicitly what is going wrong:

UICollectionView must be initialized with a non-nil layout parameter.

If you check the documentation for UICollectionView, you'll find that the only initializer is initWithFrame:collectionViewLayout:. Further, in the parameters for that initializer, you'll see:

frame

The frame rectangle for the collection view, measured in points. The origin of the frame is relative to the superview in which you plan to add it. This frame is passed to the superclass during initialization.

layout

The layout object to use for organizing items. The collection view stores a strong reference to the specified object. Must not be nil.

I've bolded the important part. You must use initWithFrame:collectionViewLayout: to initialize your UICollectionView, and you must pass it a non-nil UICollectionViewLayout object.


One way to fix this, then, would be to simply change the order of initialization you do:

UICollectionViewFlowLayout* flowLayout = [[UICollectionViewFlowLayout alloc] init];
flowLayout.itemSize = CGSizeMake(100, 100);
[flowLayout setScrollDirection:UICollectionViewScrollDirectionHorizontal];
self.collectionView = [[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:flowLayout];
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"cell"];

Note that in the above example, I've assumed you want to use self.view.frame as the frame of self.collectionView. If that's not the case, insert whatever frame you want instead.

@Semyon 2018-08-15 03:14:51

don't setCollectionViewLayout liked this: [self.collectionView setCollectionViewLayout:flowLayout]; try to set when init: [[UICollectionView alloc] initWithFrame:frame collectionViewLayout:defaultLayout];

@Koushik 2016-12-01 04:40:36

Swift 3.0 and Swift 4.0

UICollectionView

The app crashed as soon as it launched when UICollectionView is initialised

initialize like below (above viewDidLoad)

let alarmCollectionView:UICollectionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: UICollectionViewFlowLayout.init())
let layout:UICollectionViewFlowLayout = UICollectionViewFlowLayout.init()

In Method (inside viewDidLoad)

layout.scrollDirection = UICollectionViewScrollDirection.vertical
alarmCollectionView.setCollectionViewLayout(layout, animated: true)
alarmCollectionView.delegate = self
alarmCollectionView.dataSource = self
alarmCollectionView.backgroundColor = UIColor.clear
self.addSubview(alarmCollectionView)

Worked fine after initialising like this I am using Autolayout so using CGRect.zero or use your own CGRect

UICollectionViewController

In case if you are using UICollectionViewController instead of UICollectionView you need to add layout when initialization

 let  testNavController:UINavigationController = UINavigationController.init()
 let layout:UICollectionViewFlowLayout = UICollectionViewFlowLayout.init() 
 let collectionView:UICollectionViewController = UICollectionViewController.init(collectionViewLayout:layout )              
 testNavController.pushViewController(collectionView, animated: true)

@jessi 2017-11-07 06:34:07

Inside of a collection view controller in Swift 4, you cannot use this method - will get error, "Cannot override mutable property 'collectionView' of type 'UICollectionView?' with covariant type 'UICollectionView'"

@Koushik 2017-11-07 06:35:46

I'll check and update the answer if its not working thanks for notifying

@Koushik 2018-04-03 06:31:21

Better to keep a collectionview inside a UIViewController it works fine for me

@Koushik 2018-04-03 06:37:47

let layout:UICollectionViewFlowLayout = UICollectionViewFlowLayout.init() let collectionView:UICollectionViewController = UICollectionViewController.init(collectionViewLayout:layout ) testNavController.pushViewController(collectionView, animated: true) Hope this one works

@William Hu 2016-02-14 11:00:07

Just a swift version of Riley Avron's answer

    let layout = UICollectionViewFlowLayout()
    layout.itemSize = CGSizeMake(100, 100)
    let collectionView = UICollectionView(frame: CGRectZero, collectionViewLayout: layout)
    self.view.addSubview(collectionView)
    collectionView.delegate   = self
    collectionView.dataSource = self
    collectionView.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: "cellIdentifier")

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