Question

我正在尝试从Firebase调用将图像视图更改为数据库中存储的数据的数据。调用代码时，我看到

let image: UIImageView = {
    let uid = Auth.auth().currentUser?.uid
    Database.database().reference().child("users").child(uid!).observeSingleEvent(of: .value, with: { (snapshot) in
        guard let dictionary = snapshot.value as? [String : Any] else {
            return }
        let user = MyUser(dictionary: dictionary as [String : AnyObject])
        let profileImageView = UIImageView()
        profileImageView.translatesAutoresizingMaskIntoConstraints = false
        profileImageView.contentMode = .scaleAspectFill
        profileImageView.layer.cornerRadius = 30
        profileImageView.clipsToBounds = true
        profileImageView.image = UIImage(named: "app")
        profileImageView.image=#imageLiteral(resourceName: "user")
        profileImageView.loadImageUsingCacheWithUrlString(user.profileImageUrl!)
        return profileImageView
    }, withCancel: { (err) in
        print("attempting to load information")
    })
    //  return profileImageView
}()

注释掉的返回函数在哪里，我得到了错误：使用未解决的标识符'profileImageView'；您是说'provideImageData'吗？为什么？我假设由于返回值位于闭包内，因此它将知道profileImageView是什么。

Answer 1

分隔图像视图和实时数据库侦听器：

let imageView: UIImageView {
        let imageView = UIImageView()
        imageView.translatesAutoresizingMaskIntoConstraints = false
        imageView.contentMode = .scaleAspectFill
        imageView.layer.cornerRadius = 30
        imageView.clipsToBounds = true
        return imageView
}

let uid = Auth.auth().currentUser?.uid
Database.database().reference().child("users").child(uid!).observeSingleEvent(of: .value, with: { (snapshot) in
        guard let dictionary = snapshot.value as? [String : Any] else {
            return }
        let user = MyUser(dictionary: dictionary as [String : AnyObject])
        // Set the image view's image
        imageView.image = // ...
    }, withCancel: { (err) in
        print("attempting to load information")
    })

从Firebase调用数据时，void函数中出现非预期的非无效返回值

1 个答案: