基于值的字典排序并提取相应的键

Question

我有一个Swift中的字典数据结构与键，值对，我想根据值按降序对字典进行排序，然后得到对应顶部的顶部3个键3个值。

例如：

之前排序：

Dictionary<'A', 8> 
Dictionary<'B', 23> 
Dictionary<'C', 56> 
Dictionary<'D', 3> 
Dictionary<'E', 9> 
Dictionary<'F', 20> 

排序后：

Dictionary<'C', 56> 
Dictionary<'B', 23> 
Dictionary<'F', 20> 
Dictionary<'E', 9> 
Dictionary<'A', 8> 
Dictionary<'D', 3> 

所以我需要C，B和A

Answer 1

for (key,value) in (Array(arr).sorted {$0.1 < $1.1}) { 
    println("\(key):\(value)") 
} 

Answer 2

要获得前三与字典相关的键rted值，（1）由它的值的阵列排序，（2）得到的钥匙，以便从排序后的数组，然后（3）从该阵列拉出第一3个键：

let dict = ["A":8, "B":23, "C":56, "D":3, "E":9, "F":20] 

// Sort the dictionary by its values 
let sortedArray = sorted(dict, {$0.1 > $1.1}) 

// Get an array of the keys from the sorted array 
let keys = sortedArray.map {return $0.0 } 

// Get the first three keys 
let firstThreeKeys = keys[0..<3] 
println(firstThreeKeys) 

Answer 3

在夫特2你可以这样做：

let dict = ["A":8, "B":23, "C":56, "D":3, "E":9, "F":20] 

let sa = dict.sort({$0.1 > $1.1}).prefix(3).map { $0.0 } // ["C", "B", "F"]