var names = ["LiuMC","Ryoma"]
var nameWithAge = ["LiuMC":27,"Ryoma":27]
print(names)
print(nameWithAge)

输出

["LiuMC","Ryoma"]

["LiuMC": 27,"Ryoma": 27]

names是一个数组

nameWithAge是一个字典

创建空的数组和字典：

var emptyArray = [String]()

var emptyDictionary = [String:Int]()

如果类型可以推断的话 我们可以写成：

var emptyArray = []

var emptyDictionary = [:]