ios - 字典(键，值)顺序

Question

假设我有以下代码

var dictionary = ["cat": 2,"dog":4,"snake":8]; // mutable dictionary
var keys  = dictionary.keys
var values = dictionary.values
for e in keys {
    println(e)
}
for v in values {
    println(v)
}

dictionary.keys 和 dictionary.values 的顺序是否相同

例如，如果 dictionary.keys 是 "dog","snake","cat"dictionary.values 会一直是 4,8,2 吗？我在 Playground 上试了一下，结果一直显示他们有相同的顺序

Answer 1

不，不保证是同一个顺序。来自文档:

Swift’s Dictionary type is an unordered collection. The order in which keys, values, and key-value pairs are retrieved when iterating over a dictionary is not specified.