Introduction to Swift-functions

Today, we introduce swift functions, the Swift function and the C#,js are generally written, but they differ greatly from the object-c. Don't say much nonsense, just started.

1: Function-- constant parameter

  Func  function name (parameter variable: type, parameter variable: Type ... {}    Description:         1:func is a function keyword
        2:{} function Body        3: Parameter variable is the default constant type, cannot be directly modified in function function body
        That is, func a (value:string) is the same as the Func a (let value:string) notation, that is, value is a constant.

Example

/*1:func function Keyword 2: Two parameter variables  both value and value1 are constants that cannot be modified 3:sayhello ("Hello", "Swift") method of calling the function */func  SayHello (value: string,value1:string) {    var str = value + "" +  value1    println (str)}sayhello ("Hello", "swift") Run result hello Swift NOTE:----------------------error notation--------------func  SayHello (value:string,value1:string) {   value = " AA "//error notation in function parameter variable default is constant type cannot be modified}

2: Function--variable parameter

  Func function name (var  parameter variable: type,... {}    description       1:func function keyword      2:var parameter variable: type indicates that   the parameter variable is a mutable variable, not a constant and can be arbitrarily modified

Example

Func  SayHello (var value:string) {    value = "AA"//value  is modified by Var, value is variable variable   println (value)} SayHello ("Hello") running result AA

3: Function--Parameter default value

Func  function name (parameter value: type = default value) {}    
1:func is the key word for a function
2: If the parameter value is not assigned, the value of the parameter takes the default value

Example

Func SayHello (value:string = "AA") {    println ("value=\ (value)")}sayhello (Value: "10")//With parameter SayHello ()// Without running results VALUE=10VALUE=AA

Three: Function--Variable parameter

    Func function name (parameter name type ...) {}    Description:     parameter name Type ... Indicates   that the parameter can touch n parameters.

Example

Func SayHello (Values:D ouble ...) {for    temp in values{        println ("temp=\ (temp)")    }    }sayhello (1.1,1.2,1.3) Run result temp=1.1temp=1.2temp= 1.3

4: Function--External parameter name

Func  function name (parameter variable: type, parameter description  parameter variable: type)  Description:      1: The first one in the function does not need parameter Description     2: Parameter description + parameter name: type, which constitutes a parameter     invocation method      function name (parameter value, parameter description: Parameter value, parameter description: Parameter value ....) ）

Example

Joinstr value1:string is a parameter func SayHello (value:string, Joinstr value1:string) {    var  str = value + value1    println ("str= \ (str)")} SayHello ("Hello", Joinstr: "Swift") Run results Str=hello Swift

5: function input and output parameters

Description of the Func function name (inout function variable type)    :     

Example:

Func SayHello (inout value:string) {    value = "Hello Swift"}var str = "Hello" SayHello (&STR)  //pass at this time String address println (str) Run result Hello Swift

6: Function return value--tuple

/* Func function name (parameter variable: type, parameter description  parameter variable: type)-type 1:func function keyword 2: type, return type */

Example

------------------------returns the tuple func SayHello (value:string, Nums value1:string), (string,string) {        return ( value,value1)}var (A, b) =sayhello ("Hello", Nums: "Swift") println ("A=\ (A), b=\ (B)")

Run results

A=hello,b=swift

7: Function return value---function

Self-add function func  Add (num:int)->int{return    num + 1}//decrement function func zj (num:int)->int{        return num-1}//definition return function type Func  SayHello (Num:bool)--(int)->int{//Where (int)->int return parameter is shaping, return value is shaped function return        num? Add:zj}var num = 10var fun: (Int)->int = SayHello (num > 5), num = Fun (num) println ("num=\ (num)") Run result num=11

later in the article, I went back to learn from the Swift language of knowledge written to form a series. Since it is a new language, it is inevitable that there are deficiencies, and you are welcome to advise me. can also add my QQ 14,360,511,081 discussion, if you have any problem, you can also directly in QQ message sent to me, I saw the first time after you reply

Finally, a summary. Send the mind map as the end of the article

Introduction to Swift-functions