获取 Set<T> 中索引处的对象

问题描述

在 Swift 1.2 中有一个 Set 对象，您可以使用它来创建静态类型的 Set.

In Swift 1.2 there is a Set object, which you can use to create a static typed Set.

我不知道如何在某个索引处获取对象.它有一个 subscript 允许您执行以下操作:mySet[setIndex].

I cannot find out how to get the object at a certain index. It has a subscript that allows you to do the following: mySet[setIndex].

这将检索该 setIndex 处的对象.但是现在我想从某个 Int 索引中获取一个对象.

This retrieves the object at that setIndex. But now I want to get an object from a certain Int index.

var myObject = mySet[sIndex];

但是如何创建具有特定索引"的 SetIndex?

But how do I create a SetIndex with a certain 'index'?

推荐答案

Swift 3 及更新版本

您可以offsetBy:来自 .startIndex:

let mySet: Set = ["a", "b", "c", "d"]
mySet[mySet.index(mySet.startIndex, offsetBy: 2)] // -> something from the set.

Swift 2(过时)

你可以advancedBy() from .startIndex:

let mySet: Set = ["a", "b", "c", "d"]
mySet[mySet.startIndex.advancedBy(2)] // -> something from the set.

Swift 1.x(过时)

类似于String，你必须从.startIndex advance():

let mySet: Set = ["a", "b", "c", "d"]
mySet[advance(mySet.startIndex, 2)] // -> something from the set.

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