Swift Chapter 12 - methods

methods are functions.

classes , structures and enumerations all can have methods.

####Instance Methods

Local and External Parameter Names for Methods:(Local parameter is argument name and external name is in obj-c and swift . external name is wording used before the local param name.)

Ex:

class Counter {

var count: Int = 0

func incrementBy(amount: Int, numberOfTimes: Int) {

count += amount * numberOfTimes

}

}

let counter = Counter()

counter.incrementBy(5, numberOfTimes: 3) ;// here numberOfTimes is used as external name. Swift treats amount as a local name only, but treats numberOfTimes as both a local and an external name. You don’t need to define an external parameter name for the first argument value, because its purpose is clear from the function name incrementBy(_:numberOfTimes:). you can provide external

name to first parameter too. if you do not want to provide an external name for the second or subsequent parameter, use underscore character (_) as an explicit external parameter

name for that parameter.

Modifying Value Types (struct , enum) from Within Instance Methods:

no self for value type. if u want to modify the value type from within instance method use mutating behavior for that method.

Ex.

struct Point {

var x = 0.0, y = 0.0

mutating func moveByX(deltaX: Double, y deltaY: Double) {

x += deltaX

y += deltaY

;// above can be written as self = Point(x: x + deltaX, y: y + deltaY) Assigning

to self Within a Mutating Method

}

}

You can not call mutating method on const struct.

####Type Methods (static method)

Classes may also use the class keyword to allow subclasses to override the superclass’s implementation of that method.

class SomeClass {

class func someTypeMethod() {

// type method implementation goes here

}

}