按字母顺序和降序打印结构中的数组

Question

我希望我的结构首先按字母顺序打印其条目，然后按降序排列数据。所以最终的结果是：“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)
]

Answer 1

有两种方法可以做到这一点。两者都需要您将数组传递给sort（Swift 2），现在是sorted（Swift 3）。

1. 一个非常简单的实现：

   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) })
   

2. 您也可以使MyData 符合Comparable。这将比较逻辑保留在 MyData 类型中，您只需运行 sorted() 函数即可返回一个新数组：

   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()
   

这 2 个实现都输出您想要的结果：“lukes 9”、“lukes 4”、“smiths 4”