我开始学习swift是通过苹果公司提供的swift上的iBook-The swift Programming Language。这本书说要创建一个空字典,应该使用[:],就像声明数组为[]一样:

我声明一个空数组,如下所示:

let emptyArr = [] // or String[]()

但是在声明空字典时,我得到语法错误:

let emptyDict = [:]

如何声明一个空字典?


当前回答

如果要创建具有任何类型的泛型字典

var dictionaryData = [AnyHashable:Any]()

其他回答

我也在玩这个。看起来很奇怪,你可以声明一个空字典,然后像这样添加一个键/值对:

var emptyDictionary = Dictionary<String, Float>()
var flexDictionary = [:]
emptyDictionary["brian"] = 4.5
flexDictionary["key"] = "value" // ERROR : cannot assign to the result of this expression

但是你可以通过使用"Any"类型创建一个接受不同值类型的Dictionary,如下所示:

var emptyDictionary = Dictionary<String, Any>()
emptyDictionary["brian"] = 4.5
emptyDictionary["mike"] = "hello"

在Swift中声明和初始化字典

字符串字典

var stringDict: [String: String] = [String: String]()

OR

var stringDict: Dictionary<String, String> = Dictionary<String, String>()

Int字典

var stringDict: [String: Int] = [String: Int]()

OR

var stringDict: Dictionary<String, Int> = Dictionary<String, Int>()

AnyObject字典

var stringDict: [String: AnyObject] = [String: AnyObject]()

OR

var stringDict: Dictionary<String, AnyObject> = Dictionary<String, AnyObject>()

字符串数组字典

var stringDict: [String: [String]] = [String: [String]]()

OR

var stringDict: Dictionary<String, Array<String>> = Dictionary<String, Array<String>>()

字符串字典数组

var stringDict: [[String: String]] = [[String: String]]()

OR

var stringDict: Array<Dictionary<String, String>> = Array<Dictionary<String, String>>()

用这个会有用的。

var emptyDict = [String: String]()

它很方便你找路

var dict:Dictionary = [:]

你可以用以下方法将其声明为nil:

var assoc : [String:String]

好的是你已经有了排版(注意我用了var和not let,把它们看成可变和不可变)然后你可以稍后再填写:

assoc = ["key1" : "things", "key2" : "stuff"]