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
var emptyDictionary = [String: String]()
var populatedDictionary = ["key1": "value1", "key2": "value2"]
注意:如果你打算改变字典的内容，那么就把它声明为一个变量(var)。你可以将一个空字典声明为常量(let)，但如果你想要改变它，这将是毫无意义的，因为常量值在初始化后不能被改变。
其他回答
你可以像这样简单地声明它:
var emptyDict:NSMutableDictionary = [:]
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>>()
var dictList = String: swift中字典的字符串 var arrSectionTitle =字符串数组在swift
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"
迅速:
var myDictionary = Dictionary<String, AnyObject>()
