flatMap Swift中的字典詞典

Question

我有一個NSEnumerator ，它包含如下嵌套的鍵值對象：

 [ "posts" :
    ["randonRootKey1" :
        ["randomChildKey1" : [:] ]
    ], 
    ["randonRootKey2" :
        ["randomChildKey2" : [:] ],
        ["randomChildKey3" : [:] ],
    ]  
]

- posts
-- user1
--- posts
----post
-- user2
-- posts
--- post 

我想將所有用戶的所有帖子提取到一個數組中...最后一個孩子和所有父母都是字典

我想flatMap它是：

[
        ["randomChildKey1" : [:] ],
        ["randomChildKey2" : [:] ],
        ["randomChildKey3" : [:] ]
]

請注意，我已經提取了每個根字典的對象。

我努力了 ：

let sub = snapshot.children.flatMap({$0}) 

但似乎不起作用

Answer 1

 let input: [String: [String: [String: Any]]] = ["posts":
    [
        "randonRootKey1": [
            "randomChildKey1": [:],
        ],
        "randonRootKey2": [
            "randomChildKey2": [:],
            "randomChildKey3": [:],
        ]
    ]
]

var output = [String: Any]()

for dictionary in input["posts"]!.values {
    for (key, value) in dictionary {
        output[key] = value
    }
}

print(output)

[“ randomChildKey3”：[：]，“ randomChildKey2”：[：]，“ randomChildKey1”：[：]]

Answer 2

假設輸入采用這種格式

let input: [String: [String: [String: Any]]] = ["posts":
    [
        "randonRootKey1": [
            "randomChildKey1": [:],
        ],
        "randonRootKey2": [
            "randomChildKey2": [:],
            "randomChildKey3": [:],
        ]
    ]
]

使用這個

let output = input.flatMap{$0.1}.flatMap{$0.1}

您將獲得所需的輸出

[（“ randomChildKey1”，[：]），（“ randomChildKey2”，[：]），（“ randomChildKey3”，[：]）]

如果要將元組轉換為字典，請使用reduce

let output = input.flatMap{$0.1}.flatMap{$0.1}.reduce([String: Any]())
{
    (var dict, tuple) in
    dict.append([tuple.0: tuple.1])
    return dict
}

[[“” randomChildKey1“：{}]，[” randomChildKey2“：{}]，[” randomChildKey3“：{}]]