var arr:[Int] = [Int]()

//升序

arr = arr.sorted(by:<)

//降序

arr = arr.sorted(by:>)

1 func sortArray(num1: Int, num2: Int) -> Bool 
2 {
3      return num1 < num2
4 }

1 //方式1
2 arr.sort(by: sortArray)
3 //方式2
4 arr.sort(by: {(num1: Int, num2: Int) -> Bool in return num1 < num2 })

arr.sort(by: {(num1, num2) in return num1 < num2})

arr.sort(by: {return $0 < $1})

arr.sort(by: {$0 < $1})

arr.sort(){$0 < $1}

arr = arr.sorted(by:<)

1 for genre in favoriteGenres.sorted() {
2     print("\(genre)")
3 }
4 // Classical
5 // Hip hop
6 // Jazz