Lesson 3 - Method

Copy in to Playground

func show(){

print("This is example text ")

}

Screen show nothing.

Type show() and run again.

Now it show text as we want.

Copy to continue.

func multiply(a:Int,_ b:Int){

let c=a*b

print("Result is: "+String(c))

}

Add these line:

let so=10;

let so2=12;

multiply(so,so2)

Result is 120.

The codes name show(), multiply() call method or function.

The line func multiply(a:Int,_ b:Int){ declare a method, after that, we call to use.

Why need method ? When coding, we use something many times, so we put them in a method, when use, we simple call it.

Compare show() and multiply() we see show() has nothing in it’s bracket, we say it not receive parameters, multiply receive to integer numbers a, b.

If you delete dash before b in tinhnhan(), Xcode show error mark, you must add b: to before so2

Copy to below multiply()

func multiply2(a:Int, b:Int)->Int {

let c=a*b

return c

}

let so3=15;

let so4=2;

let d=multiply2(so3,so4)

print("Result is: "+String(d)).

Let compare multiply() and multiply2(), we see arrow before int at end of multiply2() different with multiply().

We say that multiply2() return a integer value. If method return value, it must has return at end of method.

Method can return a string, copy to below multiply2.

func add(a:Int,_ b:Int)->String {

let c=a+b

return"Result is " + String(c)

}

add(so3,so4)

Run to see result.

Method can return array, copy to continue.

func calculate(a:Int,_ b:Int)->[Int] {

var ar=[Int](count: 3, repeatedValue: 0)

let c=a+b;

let d=a-b;

let e=a*b;

    ar[0]=c;

    ar[1]=d;

    ar[2]=e;

return ar

}

var ar=[Int](count: 3, repeatedValue: 0)

ar=calculate(so3,so4)

Run to see result.

Method calculate() return 3 numbers array result after calculate.