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。

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"

var parking = [Dictionary < String, Double >()]

^这将为[string:double]输入添加一个字典

斯威夫特4

let dicc = NSDictionary()

//MARK: - This is empty dictionary
let dic = ["":""]

//MARK:- This is variable dic means if you want to put variable 
let dic2 = ["":"", "":"", "":""]

//MARK:- Variable example
let dic3 = ["name":"Shakeel Ahmed", "imageurl":"https://abc?abc.abc/etc", "address":"Rawalpindi Pakistan"]

//MARK: - This is 2nd Variable Example dictionary
let dic4 = ["name": variablename, "city": variablecity, "zip": variablezip]

//MARK:- Dictionary String with Any Object
var dic5a = [String: String]()
//MARK:- Put values in dic
var dic5a = ["key1": "value", "key2":"value2", "key3":"value3"]

var dic5b = [String:AnyObject]()
dic5b = ["name": fullname, "imageurl": imgurl, "language": imgurl] as [String : AnyObject]

or
//MARK:- Dictionary String with Any Object
let dic5 = ["name": fullname, "imageurl": imgurl, "language": imgurl] as [String : AnyObject]

//MARK:- More Easy Way
let dic6a = NSDictionary()
let dic6b = NSMutalbeDictionary()

var dictList = String: swift中字典的字符串 var arrSectionTitle =字符串数组在swift

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>>()