Question

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我该如何解决？

guard let imgUrl = url?.absoluteString else { return }
let imageURL = [AnyHashable("imageUrl"): imgUrl]  as [AnyHashable : Any]
let postTimeValue = [AnyHashable("postTimeStamp"): currentPostTimeStamp] as [AnyHashable: Any]
let timeValue = [AnyHashable("timeStamp"): media.timeStamp!] as [AnyHashable: Any]
let mediaRef = postRef.child("\(mediaNum)")
let caption = [AnyHashable("Caption") : caption] as [AnyHashable: Any]

let dataToUpdate = [imageURL, caption, timeValue, postTimeValue] as? [AnyHashable: Any]
mediaRef.updateChildValues(dataToUpdate!)

我在最后一行收到波纹管错误

从“ [[[AnyHashable：任何]]”到不相关类型“ [AnyHashable：任何]”的投射始终失败

在Firebase给出的这个示例中，我认为它会起作用：

let updatedUser = ["name": "Shannon", "username": "shannonrules"]
let ref = Firebase(url: "https://<YOUR-FIREBASE-APP>.firebaseio.com")

let fanoutObject = ["/users/1": updatedUser, "/usersWhoAreCool/1": updatedUser, "/usersToGiveFreeStuffTo/1", updatedUser]

ref.updateChildValues(updatedUser) // atomic updating goodness

I have read this article from firebase，并希望将其实施到我的项目中。但是，问题是我不太理解它在说什么。

有人可以简单地解释扇出功能的工作原理吗？

例如：

这是怎么回事？

let updatedUser = ["name": "Shannon", "username": "shannonrules"]
let ref = Firebase(url: "https://<YOUR-FIREBASE-APP>.firebaseio.com")

let fanoutObject = ["/users/1": updatedUser, "/usersWhoAreCool/1": updatedUser, "/usersToGiveFreeStuffTo/1", updatedUser]

ref.updateChildValues(updatedUser) // atomic updating goodness

似乎从未使用过fanoutObject。

Answer 1

您已经创建了四个[AnyHashable : Any]词典。要将这些字典作为另一个[AnyHashable : Any]字典加入，您不应该将字典包装在数组中并将case键入为[AnyHashable : Any]。使用减少和合并方法来加入所有字典

let dataToUpdate = [imageURL,postTimeValue,timeValue,caption].reduce([AnyHashable: Any]()) { (result, dict) in
    result.merging(dict, uniquingKeysWith: { (_, new) in new })
}
ref.updateChildValues(dataToUpdate)

或

var dataToUpdate = [AnyHashable: Any]()
guard let imgUrl = url?.absoluteString else { return }
dataToUpdate[AnyHashable("imageUrl") = imgUrl as Any
dataToUpdate[AnyHashable("postTimeStamp") = currentPostTimeStamp as Any
dataToUpdate[AnyHashable("timeStamp") = media.timeStamp! as Any
let mediaRef = postRef.child("\(mediaNum)")
dataToUpdate[AnyHashable("Caption") = caption as Any
ref.updateChildValues(dataToUpdate)

或

var dataToUPdate = [AnyHashable: Any]()
dataToUPdate.merge(imageURL) { (_, new) in new }
dataToUPdate.merge(postTimeValue) { (_, new) in new }
dataToUPdate.merge(timeValue) { (_, new) in new }
dataToUPdate.merge(caption) { (_, new) in new }

从'[[AnyHashable：Any]]'转换为不相关的类型'[AnyHashable：Any]'总是失败

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1 个答案: