如何追加到数组，它是在斯威夫特字典中的价值 [英] How to append to an array that is a value in a Swift dictionary

问题描述

让我们假设我有一个接受字符串作为键和一个数组作为值的字典：

Let's assume I have a dictionary that accepts a string as the key and an array as value:

var d = [String: [Int]]()
d["k"] = [Int]()

现在我想追加（）来是在阵列的 [K] 。我该怎么做呢？

Now I would like to append() to the array that is under the ["k"]. How do I do that?

[Int](d["k"]).append(1) // error
(d["k"] as [Int]).append(1) // error

我想这是一些真正的基本的，但我不出来......非常感谢！

I guess this is something really basic but I cannot figure it out... thanks a lot!

推荐答案

由于字典和数组都是结构类型，你不能修改到位数组，而是要提取并恢复它：

Because Dictionary and Array are both struct types, you can't modify the Array in place, but instead have to extract and restore it:

if var items = d["k"] {
    items.append(1)
    d["k"] = items
}
else {
    d["k"] = [1]
}

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