arrays - 从 NSFetchRequest 将字典数组转换为值数组

Question

我有一个使用 fetchRequest.resultType = .dictionaryResultType 从 NSFetchRequest 返回的字典，返回的字典是 [Any]看起来像下面这样:

teams [{
    team = Canadiens;
}, {
    team = "Maple Leafs";
}, {
    team = Penguins;
}]

我只想要一个值数组，例如 [Canadiens, "Maple Leafs", Penguins"]，如何将字典数组转换为仅包含值的数组？

完整获取

func teamNames(managedContext: NSManagedObjectContext) {
    //print("\(self) -> \(#function)")

    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Players")

    fetchRequest.fetchBatchSize = 8
    fetchRequest.propertiesToGroupBy = [#keyPath(Players.team)]
    fetchRequest.propertiesToFetch   = [#keyPath(Players.team)]
    fetchRequest.resultType          = .dictionaryResultType

    do {

        let fetchTeamNamesDictionary = try managedContext.fetch(fetchRequest)
        print("fetchTeamNamesDictionary \(fetchTeamNamesDictionary)")


    } catch let error as NSError {

        print("GoFetch|teamNames: Could not fetch. \(error), \(error.userInfo)")
    }


}

替代接受的答案:

do {

    let fetchTeamNamesArray = try managedContext.fetch(fetchRequest)

    for array in fetchTeamNamesArray {

        let teamName = (array as AnyObject).value(forKey: "team") as! String

        teamNameArray.append(teamName)

    }

Answer 1

正如您清楚地知道结果的键和值是字符串将结果强制向下转换为[[String:String]]

let teamArray = try managedContext.fetch(fetchRequest) as! [[String:String]]

然后将字典映射到键 team 的值

let teamNames = teamArray.map { $0["team"]! }