简单的实现swift中字典和数组内部排序问题，不用再单独写一个算法来实现排序了，简单快捷~

1.数组元素从小到大排序（根据元素数值大小）

let arrNumber = ["2","4","9","1","3"]
let sortedArrNumber = arrNumber.sorted { (k1, k2) -> Bool in
    return Int(k1)! < Int(k2)!
}
print(sortedArrNumber)
// ["1", "2", "3", "4", "9”]

2.数组元素从小到大排序（根据字母）

let arrLetter = ["g","a","ij","if","d"]
let sortedArrLetter = arrLetter.sorted(by: <)
print(sortedArrLetter)
// ["a", "d", "g", "if", "ij"]

3.字典键值对排序(根据key数值大小排序)

let dicKey = [
"6":"six",
"10":"ten",
"8":"eight",
"0":"zero",
"5":"five"
]
let sortedDicKey = dicKey.sorted { (k1, k2) -> Bool in
    return Int(k1.key)! < Int(k2.key)!
}
print(sortedDicKey)
// [(key: "0", value: "zero"), (key: "5", value: "five"),
// (key: "6", value: "six"), (key:"8", value: "eight"), 
// (key: "10", value: "ten")]

4.取字典中的键排序

let sortedKeys = dicKey.keys.
    return Int(k1)! < Int(k2)
}
print(sortedKeys)
// ["0", "5", "6", "8", "10"]