Question

var dist: Dictionary<String, NSObject>!
var bigDist : Dictionary<String, Dictionary<String, NSObject>>!

self.bigDist["1" as String] = self.dist

当我尝试这样做时，我收到一个错误：

fatal error: unexpectedly found nil while unwrapping an Optional value

self.dist的数据集：

Optional(["hits": 0, "name": India lags behind China in consumer spends: Stefano Ricci’s Jackie Manglani, "web": Livemint, "id": -1655, "like": 0, "iurl": http://www.livemint.com/rf/Image-222x148/LiveMint/Period2/2017/02/21/Photos/Processed/jackiemanglani2-kXhC--621x414@LiveMint.JPG, "notify": 0, "date": 201655200217, "active": 1, "type": Mark, "dateAdded": 20/02/2017, "url": http://www.livemint.com/Consumer/3NT8Vbw7BcGeoPJNMoyK5H/India-lags-behind-China-in-consumer-spends-Stefano-Riccis.html])

Answer 1

您的变量bigDist是一个隐式解包的可选项。（你用your_type!声明它。

这意味着：

它可以包含零。
您不需要使用?或!打开它。
如果你引用它并且它包含nil，你就会崩溃。

3号正在发生。

您需要创建一个空字典。尝试删除声明中的!，并在声明时创建一个空字典：

var bigDist : Dictionary<String, Dictionary<String, NSObject>> = [:]

Answer 2

您没有初始化bigDist：

var dist: Dictionary<String, NSObject>? = nil
var bigDist = Dictionary<String, Dictionary<String, NSObject>>()

self.bigDist["1"] = self.dist

无论如何，代码可能更加迅速。使用[String: NSObject]代替Dictionary<String, NSObject>（完全相同）会使代码更易于阅读，并且可以像您一样防止出现这样的错误。

var dist: [String: NSObject]? = nil
var bigDist = [String: [String: NSObject]]()

self.bigDist["1"] = self.dist

swift 3.0中的字典<string，dictionary>在尝试添加dict时给出nil

2 个答案: