Functions, assertions, enumerations, and so on in "IOS" Swift

The writing format and usage of functions and methods, enumerations, etc. are very different from those of OC or.

First, the function

1.1 No return value, invisible parameter

Func MyTest2 () {    println ("Hello")}

1.2 has a return value, a tangible parameter

Func myTest1 (Num1:int, Num2:int), string{    return String (NUM1 + num2)}

1.3 external parameters . ( equivalent to an alias for the parameter , to facilitate the identification of memory )

Func myTest3 (myNum1 num1:int, myNum2 num2:int) {    println (num1 + num2)}mytest3 (mynum1:1, mynum2:2)//Call Func MyTest4 (#num1: int, #num2: int) {   //preceded by # indicates direct parameter name as external parameter name    println (num1 + num2)}mytest4 (Num1:2, Num2:3)

1.4 Default Parameters . ( similar to C + +)

Func myTest5 (num1:int, num2:int = ten) {    println (num1+num2)}mytest5 (1) myTest5 (1, num2:22)    // The following parameter defaults to Func MyTest6 (Num1:int, _ Num2:int = ten) with formal parameters as the external parameter name   , and the external parameter name of the parameter is ignored, with the    println (num1+num2)}mytest6 before the argument ( 1, 22)

1.5 Constants and variable arguments . ( by default , Swift 's parameters are constant parameters and cannot be modified. )

Other languages, such as C, do not have this concept. You can modify the Func myTest7 (let Num1:int, Num2:int) {//    num2 = ten   //This sentence is wrong and cannot be modified    println (num1+num2)}func MyTest8 ( var num1:int, Num2:int) {  ///plus var can be changed to variable arguments.    num1 =    println (num1+num2)}

Second, assert

and C basically the same, nothing to say

var a = 10assert (a>5, "right")

third, enumeration

Not as in C , the default value is assigned to 0,1...

3.1 Enumeration format

Enum compasspoint{case North    //case indicates that a new row member is defined case South case    East case West case    A, B, C   //Multiple members can also appear on the same line}

3.2 Access Enumeration

var direct = Compasspoint.northdirect =. South       //Because the previous access, after the automatic inference. Do not write enumeration name//COMPASSPOINT.A

3.3 enumeration combined with switch use

Switch Direct{case. North:    println ("Lots of Planets has a") case. South:    println (' Watch out for Penguins ') case. East:    println ("Where The Sun Rises") case. West:    println ("Where The Skies is Blue") Default:    println ("OK")}

3.4 Associative enumeration . Values that can be associated with changes

Enum barcode{case    UPCA (int,int,int)  //associated with 3 parameters case    QRCode (String)    //associated with a string}//var Productbarcode = BARCODE.UPCA (0, 1, 2)   //This is used, associating 3 numbers.

3.5 enumerates the original values .

Enum myascii:character{   //definition type case    Tab = "\ t" case    linefeed = "\ n"}enum planet:int {case    Mercury = 1, Venus, Earth, Mars, Jupite, Saturn, Uranus, neptune}//use the Toraw method to access the original value of the enumeration println (Planet.Venus.toRaw ())   //value 2, This auto-increment//uses Fromraw to find the original enumeration member println (Planet.fromraw (2))   //Returns an optional type, which means that there is not necessarily

Evaluation: Adds new functionality to older things, simplifying the notation of functions in OC. For the use of OC or slightly do not adapt.

Reference:

The Swift programming Language

Apple Dev Center

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Functions, assertions, enumerations, and so on in "IOS" Swift