Swift Learning Notes (34)--function type __swift

(1) The function can also be assigned to a variable, what is the type of the variable at this time?

Import Foundation

func Add (a:int,b:int)-> int{return

  a+b
} Let

Anotheradd: (int,int)-> Int = add
Anotheradd (3,4)

(2) If the return value of the parameter is NULL, then how should this function type be written?

Import Foundation

func Add (a:int,b:int) {

  var c = a + b
} let

Anotheradd: (int,int)-> () = Add
anot Heradd (3,4)

Or:

Import Foundation

func Add (a:int,b:int)-> () {

  var c = a + b
} let

Anotheradd: (int,int)-> () = Add
anotheradd (3,4)

Or:

Import Foundation

func Add (a:int,b:int)-> Void {

  var c = a + b
} let

Anotheradd: (int,int)-> () = Add
anotheradd (3,4)

Or:

Import Foundation

func Add (a:int,b:int)-> void {

  var c = a + b
} let

Anotheradd: (int,int)-> void = Add
anotheradd (3,4)

(3) If this function has no parameters, what is the function type?

Import Foundation

func Add () {

} let

Anotheradd: ()-> Void = add
anotheradd ()

(4) Sorting

Import Foundation

var arr = [int] () for
_ in 1...20{

  arr.append (Int (Arc4random ()%100))
}

println (arr)

sorted (arr)
println (sorted (arr))

This is from small to large sort, if I want to from big to small, how should do it.

Import Foundation

var arr = [int] () for
_ in 1...20{

  arr.append (Int (Arc4random ()%100))
}

println ( ARR)

sorted (arr)
println (sorted (arr))

func comparetwoints (a:int,b:int)-> bool{return

  a > B
}

println (sorted (arr,comparetwoints))

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