如何访问Swift字典中的下一个键？ [英] How to access the next key in a Swift dictionary?

问题描述

我有这个代码

for (k, v) in myDict {
    println(k)
}

如何访问字典中的下一个键（例如myDict [k + 1] ）

How do I access the next key in the dictionary (e.g. myDict[k + 1])?

提前感谢

推荐答案

作为下一个关键的东西;字典没有命令。

There is no such thing as "the next key"; dictionaries have no order.

然而，您正在遍历字典...

Since, however, you are iterating through the dictionary...

for (k, v) in myDict {
    println(k)
}

我要假设你的意思是：我怎么知道，在这个迭代，什么 k 将在下一个迭代？

I'm going to assume that what you mean is: how can I know, on this iteration, what k would be on the next iteration?

一个简单的解决方案是将字典强制为数组（键值元组）：

A simple solution would be to coerce the dictionary to an array (of key-value tuples):

let arr = Array(myDict)

现在你有整数索引的东西。所以你可以这样枚举：

Now you have something with integer indexes. So you can enumerate it like this:

let arr = Array(myDict)
for (ix, (k,v)) in enumerate(arr) {
    println("This key is \(k)")
    if ix < arr.count-1 {
        println("The next key is \(arr[ix+1].0)")
    }
}

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当然，事实是，你可以枚举一个字典直接，但索引不是整数，所以它们有点难以使用。马丁·R也正在展现一种说明这一点的方法。

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The truth is, of course, that you can enumerate a dictionary directly, but indexes are not integers, so they are a little harder to work with. Martin R is also showing an approach illustrating that point.

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