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
你可以像这样简单地声明它:
var emptyDict:NSMutableDictionary = [:]
其他回答
当你在Swift中声明任何东西时，你需要显式地告诉数据类型或类型可以推断。
斯威夫特3
下面的示例声明了一个字典，其中key为Int类型，value为String类型。
方法1:初始化器
let dic = Dictionary<Int, String>()
方法二:简写语法
let dic = [Int:String]()
方法3:字典直译
var dic = [1: "Sample"]
// dic has NOT to be a constant
dic.removeAll()
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()
如果要创建具有任何类型的泛型字典
var dictionaryData = [AnyHashable:Any]()
用这个会有用的。
var emptyDict = [String: String]()
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"
