检查字典数组的值是否与数组元素列表匹配

Question

我在 Swift 中有一个数组（项目）和一个字典数组（数据）：

let items = [2, 6, 4]

var data = [
    ["id": "1", "title": "Leslie", "color": "brown"],
    ["id": "8", "title": "Mary", "color": "red"],
    ["id": "6", "title": "Joe", "color": "blue"],
    ["id": "2", "title": "Paul", "color": "gray"],
    ["id": "5", "title": "Stephanie", "color": "pink"],
    ["id": "9", "title": "Steve", "color": "purple"],
    ["id": "3", "title": "Doug", "color": "violet"],
    ["id": "4", "title": "Ken", "color": "white"],
    ["id": "7", "title": "Annie", "color": "black"]
]

我想创建一个数组，其中包含那些 "id" 等于 'items' 数组中提供的数字的字典数组。也就是我想最终得到一个数组：

var result = [
    ["id": "6", "title": "Joe", "color": "blue"],
    ["id": "2", "title": "Paul", "color": "gray"],
    ["id": "4", "title": "Ken", "color": "white"]
]

我曾尝试使用谓词，但在剧烈头痛和心脏骤停后，我并没有成功。对于这项任务，它们似乎异常复杂。我现在只想在一个简单的 for-in 循环中执行此操作。

是否有使用谓词或其他方法的巧妙方法？

Answer 1

像这样使用 filter 和 contains：

let result = data.filter { dict in
    if let idString = dict["id"], id = Int(idString) {
        return items.contains(id)
    }
    return false
}

Answer 2

试试这个，应该有效：

let items = [2, 6, 4]
var data = [
    ["id": "1", "title": "Leslie", "color": "brown"],
    ["id": "8", "title": "Mary", "color": "red"],
    ["id": "6", "title": "Joe", "color": "blue"],
    ["id": "2", "title": "Paul", "color": "gray"],
    ["id": "5", "title": "Stephanie", "color": "pink"],
    ["id": "9", "title": "Steve", "color": "purple"],
    ["id": "3", "title": "Doug", "color": "violet"],
    ["id": "4", "title": "Ken", "color": "white"],
    ["id": "7", "title": "Annie", "color": "black"]
]

var result = [Dictionary<String, String>]()

for index in 0..<data.count {
    let myData = data[index]
    let dataID = data[index]["id"]
    for i in 0..<items.count {
        if dataID == "\(items[i])" {
            result.append(myData)
        }
    }
}

for i in 0..<result.count {
    print(result[i])
}

结果是：

Answer 3

谢谢大家的回复！我认为 Eric D 的解决方案最接近我所追求的。

我终于能够在 raywenderlich.com 上找到具有良好描述的解决方案：https://www.raywenderlich.com/82599/swift-functional-programming-tutorial

使用该方法（同样，非常接近 Eric D 的建议），首先我可以将其分解为：

func findItems(value: [String: String]) -> Bool {
    return items.contains(Int(value["id"]!)!)
}
var result = data.filter(findItems)

我可以进一步减少到：

var result = data.filter {
    (value) in items.contains(Int(value["id"]!)!)
}

同样，可以将其简化为一行，如：

var result = data.filter { items.contains(Int([=12=]["id"]!)!) }

再次感谢大家！

检查字典数组的值是否与数组元素列表匹配

Check if a value of an array of dictionaries matches a list of array elements

arrays

dictionary

predicate

swift