print array in struct in alphabetical order and in descending order

问题

I would like my struct to print its entries in alphabetical order first, then arrange the data in descending order. So the final result would be: "lukes 9", "lukes 4", "smiths 4"

struct MyData {
    var company = String()
    var score: Int
}

let data = [
    MyData(company: "smiths", score: 4 ),
    MyData(company: "lukes", score: 4),
    MyData(company: "lukes", score: 9)
]

回答1:

There's 2 ways you can do this. Both would require you to pass your array to sort (Swift 2), now sorted (Swift 3).

A very easy implementation:

struct MyData {
    var company = String()
    var score: Int
}

let data = [
    MyData(company: "smiths", score: 4),
    MyData(company: "lukes", score: 4),
    MyData(company: "lukes", score: 9)
]

let sortedArray = data.sorted(by: { ($0.company, $1.score) < ($1.company, $0.score) })

You could also make MyData conform to Comparable. This keeps the comparison logic within the MyData type, and you can just run the sorted() function to return a new array:

struct MyData {
    var company = String()
    var score: Int
}

extension MyData: Equatable {
    static func ==(lhs: MyData, rhs: MyData) -> Bool {
        return (lhs.company, lhs.score) == (rhs.company, rhs.score)
    }
}

extension MyData: Comparable {
     static func <(lhs: MyData, rhs: MyData) -> Bool {
        return (rhs.company, lhs.score) > (lhs.company, rhs.score)
    }
}  

let data = [
    MyData(company: "smiths", score: 4),
    MyData(company: "lukes", score: 4),
    MyData(company: "lukes", score: 9)
]

let sortedArray = data.sorted()

These 2 implementations both output your desired result: "lukes 9", "lukes 4", "smiths 4"

来源：https://stackoverflow.com/questions/46019062/print-array-in-struct-in-alphabetical-order-and-in-descending-order

标签

swift

sorting

struct

swift3