Swift 无值字典的声明字典

我想声明字典中没有值的字典

通常我认为我应该声明可选

然而，我不知道如何设置

我该怎么做

class AppDelegate: UIResponder, UIApplicationDelegate {

    let p1: [String: String] = ["name" : "John","age" : "30"] // make p1
    let p2: [String: String] = ["name" : "Picker","age" : "32"] // make p2
    let p3: [String: String] = ["name" : "Tom","age" : "28"] // make p3
    var members: [String?: [String?:String?]] // it shows error
    ///Type 'String?' does not conform to protocol 'Hashable'

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool 
    {
        members  = ["key1":p1,"key2":p2,"key3": p3]
        // I want to put variables here.
    }

只需使用：var成员：[String:[String:String]]

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字符串和字符串？是完全不同的类型吗，字符串？不符合协议Hashable，因此不能将其用作字典中的密钥。

var members:[String:[String:String]]=[：]不能将可选类型用作字典密钥，因此请删除所有可选性，这样您就可以了