json - 如何使用 JSON 中的嵌套类型在 Swift 中表示字典

Question

假设我正在解析 JSON 并且需要将其转换为 Swift 字典。如果您注意到下面的内容，就会发现该类型是相当嵌套的。有一个帐户键，其值是另一个映射，具有嵌套数组等。我看过很多帖子建议 AnyObject？或任何？这样做的正确方法是什么？一个完整的例子就太好了。我正在使用 Alamofire/SwiftyJSON。谢谢!

    {
        "id": "20o2k2jlkja08a08",
        "username": "catlover",
        "accounts": {
            "verified_email": "false",
            "identities": [{
                "network": "facebook",
                "token": "alkdjlaksjsak",
                "avatar": "avatarUrl"
            }, {
                "network": "twitter",
                "token": "alkdjlaksjsak",
                "avatar": "avatarUrl"
            }]
        },
        "followers": "100",
        "following": "20"
    }

Answer 1

我建议您查看ObjectMapper和 AlamofireObjectMapper框架，都可以在 Cocoapods 上使用。有了它们，从 JSON 到 Swift 对象的映射真的很容易。

首先，定义 JSON 如何映射到您的对象:

import ObjectMapper

class User: Mappable {
    var id: String?
    var username: String?
    var accounts: UserAccount?
    var followers: Int?
    var following: Int?

    required init?(_ map: Map) { /* validate your JSON, etc */ }

    func mapping(map: Map) {
        self.id         <- map["id"]
        self.username   <- map["username"]
        self.accounts   <- map["accounts"]
        self.followers  <- map["followers"]
        self.following  <- map["following"]
    }
}

class UserAccount: Mappable {
    var verifiedEmail: Bool?
    var identities: [UserIdentity]?

    required init?(_ map: Map) { }

    func mapping(map: Map) {
        self.verifiedEmail  <- map["verified_email"]
        self.identities     <- map["identities"]
    }
}

class UserIdentity: Mappable {
    var network: String?
    var token: String?
    var avatar: NSURL?

    required init?(_ map: Map) { }

    func mapping(map: Map) {
        self.network    <- map["network"]
        self.token      <- map["token"]
        self.avatar     <- (map["avatar"], URLTransform())
    }
}

用法:

Alamofire.request(.GET, url)
    .responseObject { (response: Response<User, NSError>) in
        let user = response.result.value

        // Get the url to the user's avatar
        let avatarURL = user?.accounts?.identities?.first?.avatar
    }

如果您想避免所有这些 ?，只需为您的属性指定一个默认值即可。当然，只有当该属性保证出现在 JSON 中时，这才有意义:

class User: Mappable {
    var id = ""
    var username = ""
    var accounts = UserAccount()
    var followers = 0
    var following = 0

    ...
}