Question

我在当前的Swift文档中引用了这个：

您还可以遍历字典以访问其键值对。当迭代字典时，字典中的每个项都作为（键，值）元组返回，并且您可以将（键，值）元组的成员分解为明确命名的常量，以便在for-in循环的主体内使用。在这里，字典的键被分解为一个名为animalName的常量，字典的值被分解为一个名为legCount的常量。

让numberOfLegs = [“蜘蛛”：8，“蚂蚁”：6，“猫”：4]

for（animalName，   legCount）in numberOfLegs {
print("\(animalName)s have \(legCount) legs") } 
//蚂蚁有6条腿//蜘蛛有8条腿//猫有4条腿

但是，当我动态创建一个字典数组时，该代码不起作用：

let wordArray = ["Man","Child","Woman","Dog","Rat","Goose"]
var arrayOfMutatingDictionaries = [[String:Int]]()

var count = 0

while count < 6
{
    arrayOfMutatingDictionaries.append([wordArray[count]:1])
    count += 1
}

上面的例程成功地创建了字典数组，但是当我尝试按照文档显示迭代它时：

for (wordText, wordCounter) in arrayOfMutatingDictionaries

我收到错误：表达式类型[[String：Int]]含糊不清，没有更多上下文

我根本不明白。

这里的目标是拥有一个可变数组的可变字典。在程序的过程中，我想添加新的键值对，但也可以在必要时增加值。我没有和这个集合类型结婚，但我认为它会起作用。

有什么想法吗？

Answer 1

您正在尝试迭代数组，将其视为字典。你必须遍历数组然后通过你的键/值对

for dictionary in arrayOfMutatingDictionaries{
    for (key,value) in dictionary{
        //Do your stuff
    }
}

添加键/值对非常简单。

for i in 0..< arrayOfMutatingDictionaries.count{
    arrayOfMutatingDictionaries[i][yourkey] = yourvalue
}

您也可以像这样增加现有值

for i in 0..<arrayOfMutatingDictionaries.count{
    for (key,value) in arrayOfMutatingDictionaries[i]{
        arrayOfMutatingDictionaries[i][key] = value+1
    }
}

Answer 2

let wordArray = ["Man","Child","Woman","Dog","Rat","Goose"]
var arrayOfMutatingDictionaries = [[String : Int]]()

var count = 0

while count < 6 {
    arrayOfMutatingDictionaries.append([wordArray[count] : 1])
    count += 1
}

for dictionary in arrayOfMutatingDictionaries { // You missed this out!
    for (word, num) in dictionary {
    print(word, num)
    }
}

Answer 3

试试这个。而且你会得到你期望的结果。

let wordArray = ["Man","Child","Woman","Dog","Rat","Goose"]
var arrayOfMutatingDictionaries = [String]()  
//Here you are doing mistake in above line. You are creating an array of  dictionary ([[String:Int]]) in your code. And you are iterating an array of string (wordArray)

var count = 0

while count < 6
{
     arrayOfMutatingDictionaries.append(wordArray[count])
     count += 1
}

for (wordText) in arrayOfMutatingDictionaries
{
     print(wordText)
}

迭代并改变一个字典数组Swift 3

3 个答案: