Swift 检索firebase图像-ImageView

大家好，我正在尝试从firebase数据库获取我的图像，并将其作为用户的配置文件图像呈现到图像视图中。我要做的第一件事是创建一个方法来检索数组中的照片数据

class PhotoService {
    
    static func retrievePhotos(completion: @escaping ([Photo]) -> Void) {
        
        //get a databas refrence
        let db = Firestore.firestore()
        
        //get data from "photos" collection
        db.collection("photos").getDocuments { (snapshot, Error) in
            
            //check for errors
            if Error != nil {
                //error in retrieving photos
                return
            }
            
            //get all the documents
            let documents = snapshot?.documents
            
            //check that documents arent nil
            if let documents = documents {
                
                //create an array to hold all of our photo structs
                var photoArray = [Photo]()
                
                //loop through documents, get a photos struct for each
                for doc in documents {
                    
                    //create photo struct
                    let p = Photo(snapshot: doc)
                    
                    if p != nil {
                        
                        //store it in an array
                        photoArray.insert(p!, at: 0)
                        
                    }
                    
                }
                
                //pass back the photo array
                completion(photoArray) 
                
            }
            
        }
        
    }

然后调用该类并尝试在图像视图中显示图像

@IBOutlet var profilePictureImageView: UIImageView!
        
    var photos = [Photo]()
    
    override func viewDidLoad() {
        super.viewDidLoad()
                
        //call the photo service to retrieve the photos
        PhotoService.retrievePhotos { (retrievedPhotos) in
            
            //set the photo array to the retrieved photos
            self.photos = retrievedPhotos
            
            //make the image view a circle
            self.profilePictureImageView.layer.cornerRadius = self.profilePictureImageView.bounds.height / 2
            self.profilePictureImageView.clipsToBounds = true
            
            //make the image view display the photo
            var photo:Photo?
            
            func displayPhoto(photo:Photo) {
                
                //check for errors
                if photo.photourl == nil {
                    return
                }
                
                //download the image
                let photourl = URL(string: photo.photourl!)
                
                //check for erorrs
                if photourl == nil {
                    return
                }
                
                //use url session to download the image asynchronously
                let session = URLSession.shared
                
                let dataTask = session.dataTask(with: photourl!) { (data, response, Error) in
                    
                    //check for errors
                    if Error == nil && data != nil {
                        
                        //let profilePictureImageView = UIImage()
                        let image = UIImage(data: data!)
                        
                        //set the image view
                        DispatchQueue.main.async {
                            self.profilePictureImageView.image = image
                        }
                        
                    }
                    
                }
                
                dataTask.resume()  
            }
            }
        }
}

---

我不明白我做错了什么，为什么没有显示图像如果有人能向我解释这一点，并给我一个代码示例，这将是令人惊讶的，解释它就像你在向一个五年级的孩子解释一样。在这些步骤中，可以很容易地从Firebase获取图像并将其分配给ImageView

获取

照片URL的函数

//Function to get photo of loggedin User
func getUrl(Completion:@escaping((String)->())) {

    let userID = Auth.auth().currentuser?.uid
    let db = Firestore.firestore().collection("photos").document(userID)
    db.getDocument { (docSnapshot, error) in
        if error != nil {
            return
        } else {
            guard let snapshot = docSnapshot, snapshot.exists else {return}
            guard let data = snapshot.data() else {return}
            let imageUrl = data["photoUrl"] as! String
            completion(imageUrl)
            
        }
    }
}

下载图像并将其分配给图像视图

//Call this function in VC where your `ImageView` is
func getImage(Url:String){

     DispatchQueue.global().async {

         let url = URL(string: Url)
         if let data = try? Data(contentsOf: url!) {

            DispatchQueue.main.async {

                  self.profilePictureImageView.image = UIImage(data: data)

                    }
                }
            }
        }
    }
 

在

viewDidLoad

中调用这些函数，如下所示：

getUrl{(url) in
 getImage(Url:url)
} 

---

在我看来，您的代码是以下主题的直接副本。

收藏（“照片”）

里面有什么？你能用DB向我们展示这个收藏的图片吗？是的，里面是我的照片ID、我的用户ID和我的照片URL。你在Firebase存储中存储照片吗？（如果不是，你应该是）。另外，请不要发布。您刚才问了这个问题。只需从Firebase auth对象获取用户的photoUrl，这可能会容易一些。再见，非常感谢你的程序员！！！如果我见到你，我会给你一个大大的吻