相关疑难解决方法(0)

我添加UICollectionView了代码.
现在,应用程序崩溃并显示消息:UICollectionView must be initialized with a non-nil layout parameter.
你有什么想法来解决它吗？
CollectionCell是自定义类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 …

我试图从youtube教程创建一个像Facebook应用程序的应用程序.我有一个主页,用户单击BarButton打开聊天.主页工作正常,直到我单击BarButton打开聊天,它崩溃时出现以下错误消息"UICollectionView必须使用非零布局参数初始化".我是iOS开发的新手,所以无法真正理解问题究竟是什么,因为我已经有了init方法.我在AppDelegate中遗漏了一些东西,因为我有不同的观点,这很令人困惑:(.真的很感谢你的帮助.谢谢!

class ChatViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout {

override func viewDidLoad() {
    super.viewDidLoad()

    navigationItem.title = "Chats"

    collectionView?.backgroundColor = UIColor.gray

            // Do any additional setup after loading the view.
}

override func viewWillAppear(_ animated: Bool)
{
    collectionView?.register(ChatCell.self, forCellWithReuseIdentifier: "cellID")
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return 3
}

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let cell = …