Array的用法总结-swift

Araay是有序的数据集，在OC中分为不可变数组NSArray和可变数组NSMutableArray，在swift中只有常量和变量两种类型，声明成变量那就可以说明是可变的了！

学习时的具体的用法总结成如下的代码：

 //数组var arrInts = [Int]()//创建一个空数组arrInts = [];print("arrInts is of type [Int] with \(arrInts.count) items.")//// 打印 "someInts is of type [Int] with 0 items."
        var threeDoubles = Array(repeating:0.0,count:3)//创建一个带有默认值的数组print("threeDoublesArray:\(threeDoubles)")//打印 threeDoublesArray:[0.0, 0.0, 0.0]threeDoubles += threeDoubles//数组合并print("threeDoubles:\(threeDoubles)")//打印 threeDoubles:[0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
        let anotherThreeDoubles = Array(repeating: 2.5, count: 3)let sixDoubles = threeDoubles + anotherThreeDoubles;//数组合并print(sixDoubles)//打印 [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 2.5, 2.5, 2.5]//用数组字面量构造数组var goodsListArr:[String] = ["onions","eggs","apple","orange","pear","salt"]goodsListArr.append("vinegar")//在数组的末尾添加一个元素（不可以用下标访问的形式去在数组尾部添加新项）goodsListArr += ["Chocolate Spread", "Cheese", "Butter"]//给数组添加几个元素if goodsListArr.isEmpty {//判断数组是否为空print("The shopping list is empty.")} else {print("The shopping list is not empty.")}// 打印 "The shopping list is not empty."（shoppinglist 不是空的）
        let firstItem = goodsListArr[0]//根据索引 取对应的索引值print("firstItemValue:\(firstItem)")//打印 firstItemValue:onions
        goodsListArr[0] = "eight onions"//将第一个索引值替换掉// 其中的第一项现在是 "Six onions" 而不是 "onions"
        print("Replace the former results:\(goodsListArr)")//替换前的结果  Replace the former results:["eight onions", "eggs", "apple", "orange", "pear", "salt", "vinegar", "Chocolate Spread", "Cheese", "Butter"]goodsListArr[2...4] = ["Bananas", "Apples"]//将某个范围的值替换掉print("results of substitution：\(goodsListArr)")//替换后的结果 results of substitution：["eight onions", "eggs", "Bananas", "Apples", "salt", "vinegar", "Chocolate Spread", "Cheese", "Butter"]//在数组中插入元素（调用数组的insert(_:at:)方法来在某个具体索引值之前添加数据项）goodsListArr.insert("books", at: 0)//在0索引之前添加数据，现在数组第一个元素是“books”//根据索引移除数组中某一个元素
        let removeItem = goodsListArr.remove(at: 0)//将数组的第一个元素移除并获取被移除的第一项元素print("removed index 0 item is:\(removeItem)  After removing the results：\(goodsListArr)")//removed index 0 item is:books  After removing the results：["eight onions", "eggs", "Bananas", "Apples", "salt", "vinegar", "Chocolate Spread", "Cheese", "Butter"]//如果我们试着对索引越界的数据进行检索或者设置新值的操作，会引发一个运行期错误。我们可以使用索引值和数组的count属性进行比较来在使用某个索引之前先检验是否有效。除了当count等于 0 时（说明这是个空数组），最大索引值一直是count - 1，因为数组都是零起索引
        let lastItem = goodsListArr.removeLast()//将数组的最后一个元素移除并获取被移除的最后一个元素值
        print("removed last item is:\(lastItem) After removing the results：\(goodsListArr)")//打印 removed last item is:Butter After removing the results：["eight onions", "eggs", "Bananas", "Apples", "salt", "vinegar", "Chocolate Spread", "Cheese"]for item in goodsListArr{//数组的遍历
            print("数组遍历的结果：\(item)")/* 打印数组遍历的结果：eight onions数组遍历的结果：eggs数组遍历的结果：Bananas数组遍历的结果：Apples数组遍历的结果：salt数组遍历的结果：vinegar数组遍历的结果：Chocolate Spread数组遍历的结果：Cheese*/}//使用enumerated()方法来进行数组遍历。enumerated()返回一个由每一个数据项索引值和数据值组成的元组。我们可以把这个元组分解成临时常量或者变量来进行遍历(可以同时d得到每个数据项的值和索引值)for(index,value) in goodsListArr.enumerated(){print("Item \(String(index + 1)): \(value)")/*打印Item 1: eight onionsItem 2: eggsItem 3: BananasItem 4: ApplesItem 5: saltItem 6: vinegarItem 7: Chocolate SpreadItem 8: Cheese*/}