如何在Swift中创建类似于排序，过滤，缩小和映射的Array方法? [英] How can I create an Array method in Swift similar to sort, filter, reduce, and map?

问题描述

在研究封闭性时，我有一个问题.

I have a question, during study of closure.

我想要像数组类型那样使数据类型闭合方法 .sort()、. filter()、. reduce()、. map()

I want make datatypes closure method like in array types .sort(), .filter(), .reduce(), .map()

但是我该怎么做. 它的数据类型不是类.

But how can I make this things. Its datatype not a class.

我想做

array.somemethod({closure})

不是

Somefunc(input: array, closure : { .... })

-

我可以快速制作数据类型方法吗?

Can I make datatype method in swift?

否则，我只能使用func吗?

otherwise, I can use func only?

推荐答案

您只需要扩展Array并传递一个闭包作为方法参数即可.假设您想创建一个可变方法，使其与过滤器相反(根据条件删除数组的元素):

You just need extend Array and pass a closure as your method argument. Lets say you would like to create a mutating method to work as the opposite of filter (to remove elements of your array based on a condition):

extension Array {
    mutating func removeAll(where isExcluded: (Element) -> Bool)  {
        for (index, element) in enumerated().reversed() {
            if isExcluded(element) {
                remove(at: index)
            }
        }
    }
}

扩展RangeReplaceableCollection的另一个选项:

extension RangeReplaceableCollection where Self: BidirectionalCollection {
    mutating func removeAll(where predicate: (Element) throws -> Bool) rethrows {
        for index in indices.reversed() where try predicate(self[index]) {
            remove(at: index)
        }
    }
}

---

用法:

---

Usage:

var array = [1, 2, 3, 4, 5, 10, 20, 30]
array.removeAll(where: {$0 > 5})
print(array)   // [1, 2, 3, 4, 5]

或使用结尾闭包语法

array.removeAll { $0 > 5 }

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