黑色UICollectionView

Question

我一直在学习如何使用UICollection视图。我创建了一个新的单元控制器，并在main.storyboard中将集合视图单元格标识为“UICollectionView”。每当我轻触UICollectionView控制器(通过TapBar控制器)时，我都会看到黑屏。我目前正在使用Firebase导入/导出数据。谢谢你的帮助!

  class UserCollectionViewController: UICollectionViewController {
        var databaseRef = FIRDatabase.database().reference()
        var usersDict = NSDictionary?()

        var userNameArray = [String]()
        var userImageArray = [String]()

        override func viewDidLoad() {
            super.viewDidLoad()


            self.databaseRef.child("user_profile").observeEventType(.Value, withBlock :{
                (snapshot) in
                self.usersDict = snapshot.value as? NSDictionary
                for(userId,details) in self.usersDict! {
                    let img = details.objectForKey("profile_pic_small") as! String
                    let name = details.objectForKey("name") as! String
                    let firstName = name.componentsSeparatedByString(" ")[0]
                    self.userImageArray.append(img)
                    self.userNameArray.append(firstName)
                    self.collectionView?.reloadData()
                }


            })

        }
            override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
                return 1
            }

            override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
                return self.userImageArray.count
            }

            override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

            let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath) as! CollectionViewCell
            return cell


                let imageUrl = NSURL(string: userImageArray[indexPath.row])
                let imageData = NSData(contentsOfURL: imageUrl!)

                cell.userImage.image = UIImage(data: imageData!)
                cell.userName.text = userNameArray[indexPath.row]

                return cell
        }

    }

Answer 1

在单元中放置一个标签(将其相对于单元的约束设置为0,0,0,0 )，然后向其添加imageView和UIView。另外，别忘了确认委托和数据源。