从 JSON 结果转换为 NSDictionary[] 的数据会引发 EXC_BAD_INSTRUCTION 运行时错误

Question

在被解析为 NSDictionary 之后，我的 Swift 代码中收到了以下 JSON。在我的函数中，我试图将“结果”块中的 JSON 对象提取为 NSDIctionary[]，但这会引发运行时错误。我不明白为什么，因为这只是几天前的工作。

{
"results": [
    {
        "id": "3",
        "name": "The National",
        "slug": "thenational",
        "facebook_url": "https://www.facebook.com/thenationalofficial/",
        "twitter_url": "https://twitter.com/The_National",
        "profile_image": "http://example.staging.com/media/profile_image/thumbnail_263x263/1352756032.jpg",
        "_type": "artist",
        "resource_uris": {
        }
    },
    {
        "id": "5",
        "name": "Mayer Hawthorne",
        "slug": "mayerhawthorne",
        "facebook_url": "https://www.facebook.com/MayerHawthorne",
        "twitter_url": "https://twitter.com/MayerHawthorne",
        "profile_image": "http://example.example.com/media/profile_image/thumbnail_263x263/1352755133.png",
        "_type": "artist",
        "resource_uris": {
        }
    },
    {
        "id": "20",
        "name": "I Play Maracas",
        "slug": "iplaymaracas",
        "facebook_url": "",
        "twitter_url": "",
        "profile_image": "http://staging.wedemand.com/images/en/img-list-home.gif",
        "_type": "artist",
        "resource_uris": {
            "_demanded_by": null,
            "demand_url": "http://ec2-54-86-17-163.compute-1.amazonaws.com/artists/20/?demand=1&access_token={}",
            "dismiss_url": "http://ec2-54-86-17-163.compute-1.amazonaws.com/artists/20/?demand=0&access_token={}"
        }
    },
    {
        "id": "35",
        "name": "Black SuperHeros",
        "slug": "blacksuperheros",
        "facebook_url": "",
        "twitter_url": "",
        "profile_image": "http://staging.example.com/images/en/img-list-home.gif",
        "_type": "artist",
        "resource_uris": {
        }
    },
    {
        "id": "49",
        "name": "Ayman Elgadi",
        "slug": "aymanelgadi",
        "facebook_url": "",
        "twitter_url": "",
        "profile_image": "http://staging.example.com/images/en/img-list-home.gif",
        "_type": "artist",
        "resource_uris": {
        }
    },
    {
        "id": "8874",
        "name": "Lauri",
        "slug": "lauri",
        "facebook_url": "http://www.facebook.com/hughlaurieblues",
        "twitter_url": "http://twitter.com/hughlaurieblues",
        "profile_image": "http://staging.example.com/media/profile_image/thumbnail_263x263/lauri_profilepic.jpg",
        "_type": "artist",
        "resource_uris": {
        }
    }
]
}

我的 IOS-Swift 代码在被 AFNetworking 库解析后接收到 NSDictionary 对象，并传递给将结果数组转换为 NSDictionary[] 的函数，现在抛出运行时错误，而之前这可以工作。

(operation: AFHTTPRequestOperation!, responseObject: AnyObject!) in println("JSON: " + responseObject.description)

var jsonResult: NSDictionary = responseObject as NSDictionary

这个 jsonResult 被传递给下面的函数，它试图转换为 NSDictionary[]

let allResults: NSDictionary[] = results["results"] as NSDictionary[]

更新： 我打印了结果对象的类，因为它作为 __NSCFDictionary 返回。

What is an NSCFDictionary? 是关于此的讨论，并说要像使用 NSDictionary 一样使用它，但在我的情况下它不起作用。

Answer 1

results 的值不是 JSON 中的字典，它是一个数组。你应该用这样的东西得到它；

let allResults: NSArray = results["results"] as NSArray