## Swift 容器類 Collections 所謂的容器類，就是程序中的數據結構，來承載我們app中的數據。 ### 數組 Array * 有序的數據序列 例如：`var numbers = [1, 2, 3, 4, 5]` 或者 `var vowels = ["A", "B", "C", "D", "E"]` ### 字典 Dictionary * 鍵 -> 值數據對 例如：`var dir1 = ["key1":"val", "key2":"val2"]` ### 集合 Set * 無序 * 唯一性 * 快速查找 * 提供集合操作 例如：`var set1 = [1, 2, 3]` ### for-in 遍歷 #### 對Range使用for-in ``` for number in 1..<10{ number } ``` #### 對String.charcaters使用for-in ``` for c in "Hello".characters { c } ``` #### 對Array使用for-in ``` var vowels = ["a", "b", "c", "d"] for vowel in vowels { vowel } for (key, vowel) in vowels.enumerated() { key vowel } ``` #### 對Dictionary使用for-in ``` var dict: Dictionary<Int,String> = [1:"a",2:"b",3:"d"] // 遍歷字典鍵 for key in dict.keys { key } // 遍歷字典值 for value in dict.values { value } // 遍歷字典鍵值 for (key, value) in dict { key value } ``` #### 對Set使用for-in ``` var set = Set(["a", "b", "c", "d"]) for vowel in set { vowel } ```