swift - 合并 reduce 和 filter Swift

Question

我有 2 个代码片段:

let names = ["Scarlet", "Stan", "Mike", "Walter", "Jessie"]

let reduceStr = names.reduce("", { x, y in

    x + y
})

print(reduceStr)


let reduceStrWithFilter = names.filter { (x) -> Bool in

    return x.characters.count > 5
}

我有点不适应 swift 语法，我想先结合这两个函数来制作过滤器，然后将 reduce 应用于过滤后的数组。

Answer 1

这比你想象的要容易:

let names = ["Scarlet", "Stan", "Mike", "Walter", "Jessie"]

var bothReducedAndFiltered = names.filter { $0.characters.count > 5 }.reduce("", +)
print(bothReducedAndFiltered)

或者如果你真的想拆分 2:

var filtered =  names.filter { $0.characters.count > 5 }
var reducedAfterFilter = filtered.reduce("", +)
print(reducedAfterFilter)

或者更短的解决方案:

var bothReducedAndFiltered = names.filter { $0.characters.count > 5 }.joined()

这会打印: ScarletWalterJessie

解释:在 filter 和 reduce 方法中，$0 表示迭代中的当前元素。

希望对您有所帮助!