arrays - 从字典中获取键并将它们映射到数组

Question

我正在尝试构建一个符合我的标题所说的闭包。我的代码运行了，但没有打印出我预期的结果。

var names: [String] = []
var namesAndAges = ["Tom": 25, "Michael": 35, "Harry": 28, "Fabien": 16]

var ofAge = namesAndAges.filter { namesAndAges in namesAndAges.value > 18 }

var addNames = ofAge.map { ofAge in names.append(ofAge.key) }

print(addNames) //this prints [(), (), ()]

Answer 1

基本上您在滥用过滤器和映射方法。试试这个:

var names: [String] = []
var namesAndAges = ["Tom": 25, "Michael": 35, "Harry": 28, "Fabien": 16]

var ofAge = namesAndAges.filter { $0.value > 18 }

var addNames = ofAge.map { $0.key }

print(addNames) //this prints ["Michael", "Harry", "Tom"]