从 Firestore 数据添加子视图 (UIKit)

Question

我遇到无法将多个子视图添加到 UIView 的问题。运行我的代码时，我成功地能够看到来自 Firestore 的数据。 我也能够在我的 canvasView 上看到一个子视图，但之后没有其他任何东西出现。

   func fetchObjects() {
    let index = IndexPath(row: 1, section: 0)
    let cell: BookCell = self.backgroundTable.cellForRow(at: index) as! BookCell
    let newButton = cell.bookButton
    guard let userID = Auth.auth().currentUser?.uid else { return }
  
    COLLECTION_BOOKS.document(userID).collection("collections").getDocuments { (snapshot, err) in
        if let err = err {
            print("Error getting documents: \(err)")
        } else {
            for document in snapshot!.documents {
                let imageURL = document.get("imageURL") as! String
                let xLocation = document.get("xLocation") as! Double
                let yLocation = document.get("yLocation") as! Double
               
                let buttonPhotoString = imageURL
                if let url = URL(string: buttonPhotoString) {
                    let data = try? Data(contentsOf: url)
                    if let imageData = data {
                  
                        guard let image = UIImage(data: imageData) else { return }
                        newButton.setImage(image, for: .normal)
                        newButton.frame.origin.x = xLocation
                        newButton.frame.origin.y = yLocation
                        cell.canvasView.addSubview(newButton)
                    } else {
                        print("Unable to get image data")
                    }
                } else {
                    print("Unable to process url string")
                }
            }
        }
        
    }
}

Answer 1

更新了答案。 我删除了引用单元格按钮的常量，而是在循环中创建了一个新按钮。

func fetchObjects() {
let index = IndexPath(row: 1, section: 0)
let cell: BookCell = self.backgroundTable.cellForRow(at: index) as! BookCell
guard let userID = Auth.auth().currentUser?.uid else { return }

COLLECTION_BOOKS.document(userID).collection("collections").getDocuments { (snapshot, err) in
    if let err = err {
        print("Error getting documents: \(err)")
    } else {
        for document in snapshot!.documents {
            var new = UIButton()
            let imageURL = document.get("imageURL") as! String
            let xLocation = document.get("xLocation") as! Double
            let yLocation = document.get("yLocation") as! Double
           
            let buttonPhotoString = imageURL
            if let url = URL(string: buttonPhotoString) {
                let data = try? Data(contentsOf: url)
                if let imageData = data {
              
                    guard let image = UIImage(data: imageData) else { return }
                    new = UIButton(frame: CGRect(x: 170, y: 142, width: 70, height: 70))
                        new.setImage(image, for: .normal)
                        new.frame.origin.x = xLocation
                        new.frame.origin.y = yLocation
                    cell.canvasView.addSubview(new)
                } else {
                    print("Unable to get image data")
                }
            } else {
                print("Unable to process url string")
            }
        }
    }
    
  }
}