如何通过键过滤 NSArray：值，即在 NSDictionary

Question

我试图弄清楚如何通过值“名称”过滤掉 NSArrays 的字典

// Is an Array of a dictionary, by key : values

var teamFilteredList = [[String:Any]]()
var teamList = [[String:Any]]() 

获取：

    let string = "https://api/connect/"
    let url = NSURL(string: string)
    let request = NSMutableURLRequest(url: url! as URL)
    request.httpMethod = "GET"
    let session = URLSession.shared
    let tache = session.dataTask(with: request as URLRequest) { (data, response, error) -> Void in
        if let jsonObj = try? JSONSerialization.jsonObject(with: data!, options: .allowFragments) as! NSArray {
            print(jsonObj)
            teamList = jsonObj as! [[String : Any]]

            DispatchQueue.main.async {
                self.teamCollectionView.reloadData()
            }
        }
    }
    tache.resume()

此代码是结果并被放入 teamList

JSON：

({
    id = 1;
    logo = "testLogo";
    name = "testTeam1";
    "url" = "https://example.com";
},
    {
    id = 2;
    logo = "testLogo";
    name = "testTeam2";
    "url" = "https://example.com";
},
    {
    id = 3;
    logo = "testLogo";
    name = "testTeam3";
    "url" = "https://example.com";
})

放入 teamList 后的外观示例：

let example = [[id: "1", logo: "image", name: "testTeam1", url: "https"], [id: "2", logo: "image", name: "testTeam2", url: "https"]] 

试图过滤的代码：

 let array2Name = teamFilteredList.flatMap { $0["name"] }
    teamFilteredList = teamList.reduce(teamFilteredList, { result, value in
        !array2Name.contains(where: { $0 as! _OptionalNilComparisonType == value["testTeam3"] }) ? result + [value]: result
    })

到目前为止，这段代码很糟糕。但是网上没有其他东西可以告诉我如何做到这一点。所以我被卡住了。

导致崩溃：

无法转换“__NSCFString”类型的值

更新：

我有一个集合视图，它是由 NSURL 从获取中填充的，它给了我一个充满 NSArrays 的字典，我想通过一个已经在 NSArray 索引中的值过滤掉该字典中的所有 NSArray 索引键：“名称”

此链接最终答案中已回答的问题，但它不是最新的并且会产生错误。 here

Answer 1

使用自定义结构和JSONDecoder 会容易得多

创建一个结构

struct Team : Decodable {
    let id : Int
    let logo : String
    let name : String
    let url : URL
}

创建数组

var teamList = [Team]()
var teamFilteredList = [Team]()

解码 JSON

let string = "https://api/connect/"
let url = URL(string: string)!
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
    if let error = error { print(error); return }
    do {
        self.teamList = try JSONDecoder().decode([Team].self, from: data!)
        DispatchQueue.main.async {
            self.teamCollectionView.reloadData()
        }
    } catch {
        print(error)
    }
}
task.resume()

并过滤数组

teamFilteredList = teamList.filter{ $0.name == "testTeam3" }

Answer 2

尝试使用这个谓词

teamFilteredList.filter({ fromDict in return !array2Name.contains(where: { $0 == fromDict["name"] as? String ?? ""})})

诀窍在于 Swift 的错误没有表现力。它说don't use where，为什么？因为编译器真的需要一个字符串，因为你的闭包不正确。

如果array2Name 也是字典。尝试将where 子句更改为：

where: { ($0["name"] as? String ?? "<<Empty1>>") == (fromDict["name"] as? String ?? "<<Empty2>>") }

所以整个函数是：

teamFilteredList.filter({ fromDict in return !array2Name.contains(where: { ($0["name"] as? String ?? "<<Empty1>>") == (fromDict["name"] as? String ?? "<<Empty2>>") })})

如果你想学习更有效的函数式编程并且不介意一些 JavaScript，试试这个

Learn Effective Functional Programming in JavaScript)