Firebase存储图像回来空白

Question

我知道我错过了一些简单的事情，但我花了数小时试图弄清楚。我的所有代码都能正常工作，并且运行正常，但没有图像。它是空白的。为什么？

func loadMembers4(completion: @escaping ([User]) ->()) { 
    var usersArray = [User]() 
    ref.child("members").observeSingleEvent(of: .value, with: { (snapshot) in 
     for item in snapshot.children { 
      if let snap = item as? FIRDataSnapshot { 
       if let value = snap.value as? [String : Any] { 
        let birthday = value["birthday"] as! Int 
        let childParent = value["childParent"] as! String 
        let firstName = value["firstName"] as! String 
        let gender = value["gender"] as! String 
        let passcode = value["passcode"] as! Int 
        let profileImageUrl = value["profileImageUrl"] as! String 

        // get image 

        self.loadMemberProfilePict4(userProfileImageUrl: profileImageUrl, completion: { (userImage) in 
         let user = User(profilePhoto: userImage, userFirstName: firstName, userBirthday: birthday, userPasscode: passcode, userGender: gender, isUserChildOrParent: childParent) 
         usersArray.append(user) 
         usersArray.sort(by: {$0.birthday > $1.birthday}) 
        }) 
       } 
      } 
     } 
     completion(usersArray) 
    }) 
} 

func loadMemberProfilePict4(userProfileImageUrl: String, completion: @escaping (UIImage) ->()) { 
    var userImage = UIImage() 
    let storageRef = FIRStorage.storage().reference(forURL: userProfileImageUrl) 
    print(userProfileImageUrl) 
    storageRef.data(withMaxSize: 1 * 1024 * 1024, completion: { (imageData, error) in 
     let profileImage = UIImage(data: imageData!) 
     userImage = profileImage! 
    }) 
    completion(userImage) 
} 

而且ViewDidLoad方法：

loadMembers4 { (usersArray) in 
     print(usersArray.count) 
     self.currentUserName = usersArray[1].firstName 
     self.instructionsLabel.text = "Choose daily and weekly job assignments for \(usersArray[1].firstName)." 
     self.userImage.image = usersArray[1].photo 
    } 

我知道的影像从火力地堡越来越牵强，因为当我在loadMemberProfilePict4功能打印userProfileImageUrl，它打印出正确的火力地堡的存储位置。但是当我在ViewDidLoad中调用它时，图像显示为空白。空空如也。

任何想法？再次，我确信这是一件简单的事，我可以忽略，只需要一双新的眼睛来指出它。谢谢！

编辑＃1：

如果我打印出来这是怎么回事在loadMembersProfilePict4方法，它显示以下内容：

func loadMemberProfilePict4(userProfileImageUrl: String, completion: @escaping (UIImage) ->()) { 
    var userImage = UIImage() 
    let storageRef = FIRStorage.storage().reference(forURL: userProfileImageUrl) 
    print("UserProfileURL: ",userProfileImageUrl)  // returns 4 strings of https://firebasestorage.google... (all correct) 

    storageRef.data(withMaxSize: 1024 * 1024) { (imageData, error) in 
     print("ImageData: ",imageData ?? "no data found!")   // returns 21061 bytes, 7668 bytes, 44887 bytes, 8995 bytes (is this right?) 

     let profileImage = UIImage(data: imageData!) 
     userImage = profileImage! 
     print("UserImage: ",userImage.images ?? "no images found!")  // returns "no images found!" 
    } 
    completion(userImage) 
} 

所以它似乎是莫名其妙的形象是没有得到正确加载？我不明白。我在我的项目的另一部分使用完全相同的代码，并且它加载用户图像就好了。到底是怎么回事？ AARGH！太令人沮丧了。

Answer 1

因此，在花了两天的时间试图找出解决方案后，我得出结论，由于某些原因，Swift不允许我制作嵌入式@escaping关闭。我可以创建单独的@escaping关闭，它们都可以工作，但是如果我将其中一个放入另一个，则第二个将无法正确执行。

所以这是我落得这样做：

功能＃1：获取用户数据火力地堡，包括URL字符串存储在火力地堡存储用户的照片。

func loadMembers(completion: @escaping ([UserClass]) ->()) { 
    var usersArray = [UserClass]() 
    ref.child("members").observeSingleEvent(of: .value, with: { (snapshot) in 
     for item in snapshot.children { 
      if let snap = item as? FIRDataSnapshot { 
       if let value = snap.value as? [String : Any] { 
        let birthday = value["birthday"] as! Int 
        let childParent = value["childParent"] as! String 
        let firstName = value["firstName"] as! String 
        let gender = value["gender"] as! String 
        let passcode = value["passcode"] as! Int 
        let profileImageUrl = value["profileImageUrl"] as! String 

        let user = UserClass(userProfileImageURL: profileImageUrl, userFirstName: firstName, userBirthday: birthday, userPasscode: passcode, userGender: gender, isUserChildOrParent: childParent) 
        usersArray.append(user) 
        usersArray.sort(by: {$0.birthday > $1.birthday}) 
       } 
      } 
     } 
     completion(usersArray) 
    }) 
} 

功能＃2：从第一函数采用URL字符串并且使用它来从火力地堡加载用户的图像。但是，这并没有给我完整的图像阵列，因为它一次递增一个地加载它们。而不是给我count: 4，它会给我count: 1, count: 2, count: 3, count: 4。

因此，当我加载视图控制器时，图像会循环通过每个用户，然后登陆到正确的一个。不理想。

// WORKS BEST, BUT IMAGES CYCLE THRU ALL USERS 
func loadMemberProfilePict(userImageURL: String, userFirstName: String, userBirthday: Int, userPasscode: Int, userGender: String, userChildParent: String, completion: @escaping ([User]) ->()) { 
    let storageRef = FIRStorage.storage().reference(forURL: userImageURL) 
    storageRef.data(withMaxSize: 1 * 1024 * 1024, completion: { (data, error) in 
     let pic = UIImage(data: data!) 
     let user = User(profilePhoto: pic!, 
         userFirstName: userFirstName, 
         userBirthday: userBirthday, 
         userPasscode: userPasscode, 
         userGender: userGender, 
         isUserChildOrParent: userChildParent) 
     self.users.append(user) 
     self.users.sort(by: {$0.birthday > $1.birthday}) 
     completion(self.users) 
    }) 
} 

功能＃3：导致这个功能，我用一个简单的'if'声明等到所有用户都在视图中显示它们之前被加载。

在ViewDidLoad：

loadMembers { (usersArray) in 
     var memberImageCount = 0 

     for user in usersArray { 
      self.loadMemberProfilePict(userImageURL: user.imageURL, userFirstName: user.firstName, userBirthday: user.birthday, userPasscode: user.passcode, userGender: user.gender, userChildParent: user.childParent, completion: { (usersIntermediateArray) in 
       memberImageCount += 1 
       if memberImageCount == usersArray.count { 
        self.users = usersIntermediateArray 
        self.userImage.image = self.users[3].photo 
        self.currentUserName = self.users[3].firstName 
        self.instructionsLabel.text = "Choose daily and weekly job assignments for \(self.users[3].firstName)." 
        self.navigationItem.title = self.users[3].firstName 
       } 
      }) 
     } 
    } 

我不知道这是不是最好的做法，但它的功能，我希望它可以帮助别人，将来谁可能有同样的问题。

Answer 2

I simply put two line for userName and image of viewDidLoad() method into completion block of respective method. Remove that lines from viewDidLoad().

func loadMemberProfilePict4(userProfileImageUrl: String, completion: @escaping (UIImage) ->()) { 
    var userImage = UIImage() 
    let storageRef = FIRStorage.storage().reference(forURL: userProfileImageUrl) 
    print(userProfileImageUrl) 
    storageRef.data(withMaxSize: 1 * 1024 * 1024, completion: { (imageData, error) in 
     let profileImage = UIImage(data: imageData!) 
     userImage = profileImage! 
     self.userImage.image = profileImage 
    }) 
    completion(userImage) 
} 

For Username put other line in completion block of loadMembers4()

func loadMembers4(completion: @escaping ([User]) ->()) { 
    var usersArray = [User]() 
    ref.child("members").observeSingleEvent(of: .value, with: { (snapshot) in 
     for item in snapshot.children { 
      if let snap = item as? FIRDataSnapshot { 
       if let value = snap.value as? [String : Any] { 
        let birthday = value["birthday"] as! Int 
        let childParent = value["childParent"] as! String 
        let firstName = value["firstName"] as! String 
        let gender = value["gender"] as! String 
        let passcode = value["passcode"] as! Int 
        let profileImageUrl = value["profileImageUrl"] as! String 

        // get image 

        self.loadMemberProfilePict4(userProfileImageUrl: profileImageUrl, completion: { (userImage) in 
         let user = User(profilePhoto: userImage, userFirstName: firstName, userBirthday: birthday, userPasscode: passcode, userGender: gender, isUserChildOrParent: childParent) 
         **self.currentUserName = user.firstName** 
         self.instructionsLabel.text = "Choose daily and weekly job assignments for \(user.firstName)." 
         usersArray.append(user) 
         usersArray.sort(by: {$0.birthday > $1.birthday}) 
        }) 
       } 
      } 
     } 
     completion(usersArray) 
    }) 
} 

Answer 3

这就是为什么你的代码是空白：

// #1 
var userImage = UIImage() 
// #2 
storageRef.data(withMaxSize: 1 * 1024 * 1024, completion: { (imageData, error) in 
    // #4 
    let profileImage = UIImage(data: imageData!) 
    userImage = profileImage! 
}) 
// #3 
completion(userImage) 

有一种竞争状态，因为下载的数据是异步的。这意味着您在图像下载之前返回空图像。通过这样做来解决它：

// #1 
var userImage = UIImage() 
// #2 
storageRef.data(withMaxSize: 1 * 1024 * 1024, completion: { (imageData, error) in 
    // #3 
    completion(UIImage(data: imageData!)) 
}) 

应该解决问题。