## Swift 容器类 Collections 所谓的容器类，就是程序中的数据结构，来承载我们app中的数据。 ### 数组 Array * 有序的数据序列 例如：`var numbers = [1, 2, 3, 4, 5]` 或者 `var vowels = ["A", "B", "C", "D", "E"]` ### 字典 Dictionary * 键 -> 值数据对 例如：`var dir1 = ["key1":"val", "key2":"val2"]` ### 集合 Set * 无序 * 唯一性 * 快速查找 * 提供集合操作 例如：`var set1 = [1, 2, 3]` ### for-in 遍历 #### 对Range使用for-in ``` for number in 1..<10{ number } ``` #### 对String.charcaters使用for-in ``` for c in "Hello".characters { c } ``` #### 对Array使用for-in ``` var vowels = ["a", "b", "c", "d"] for vowel in vowels { vowel } for (key, vowel) in vowels.enumerated() { key vowel } ``` #### 对Dictionary使用for-in ``` var dict: Dictionary<Int,String> = [1:"a",2:"b",3:"d"] // 遍历字典键 for key in dict.keys { key } // 遍历字典值 for value in dict.values { value } // 遍历字典键值 for (key, value) in dict { key value } ``` #### 对Set使用for-in ``` var set = Set(["a", "b", "c", "d"]) for vowel in set { vowel } ```