ios - Swift:合并具有重复键但唯一值的字典数组

Question

我有一个包含相同键但值不同的字典数组。我想合并这些字典并添加相同键的所有值，如下所示:

var arrayofDict = [["2019":"A"],["2019":"B"],["2019":"C"],["2018":"A"],["2018":"c"],["2017":"A"],["2017":"B"],["2017":"C"],["2016":"A"],["2015":"A"],["2015":"B"]]

作为字典的预期结果:

   var newDict = [["2019":["A","B","C"]],["2018":["A","C"]],["2017":["A","B","C"]],["2016":["A"]],["2015":["A","B"]]]

Answer 1

这显示了如何构建单个词典。您的“预期结果”是一个数组。这是您真正期望的，还是想要一个数组？

您可以迭代字典项并建立字典条目:

var arrayofDict = [["2019":"A"],["2019":"B"],["2019":"C"],["2018":"A"],["2018":"c"],["2017":"A"],["2017":"B"],["2017":"C"],["2016":"A"],["2015":"A"],["2015":"B"]]

var result = [String : [String]]()
for dict in arrayofDict {
    for (key, value) in dict {
        result[key, default: []].append(value)
    }
}

print(result)

["2016": ["A"], "2018": ["A", "c"], "2015": ["A", "B"], "2019": ["A", "B", "C"], "2017": ["A", "B", "C"]]

或者，如果需要数组:

let result2 = result.map { [$0.key: $0.value] }
print(result2)

[["2015": ["A", "B"]], ["2016": ["A"]], ["2019": ["A", "B", "C"]], ["2018": ["A", "c"]], ["2017": ["A", "B", "C"]]]