Swift Constructor (initializer) and deinitializer (deinitializer)

To initialize instance attributes of struct, class, and other types.

Default constructor

struct Fahrenheit {var temperature: Doubleinit(){temperature = 32.0} } 

VaR F = Fahrenheit () // call the default constructor Init (). No parameter is returned.

println("The default temperature   is \(f.temperature)°Fahrenheit")// prints "The default temperature is 32.0° Fahrenheit"

Custom Constructor

 

The definition class has two constructors: Init (fromfahrenheit :) and init (fromkelvin :)

 

struct Celsius {var temperatureInCelsius: Double = 0.0 init(fromFahrenheit fahrenheit: Double) { temperatureInCelsius = (fahrenheit - 32.0)/ 1.8 } init(fromKelvin kelvin: Double) {  temperatureInCelsius = kelvin -273.15   } } let boilingPointOfWater = Celsius(fromFahrenheit:212.0) // boilingPointOfWater.temperatureInCelsius is 100.0 let freezingPointOfWater =Celsius(fromKelvin:273.15) // freezingPointOfWater.temperatureInCelsius is 0.0

Deinitializer)

The Destructor is opposite to the constructor and called when the object is released. Use the keyword deinit. The syntax is as follows:

deinit {// perform thedeinitialization}

Instance:

 

class Player { var coinsInPurse:Int init(coins: Int) {println("call init")coinsInPurse= coins }func winCoins(coins: Int) {coinsInPurse+= 10}deinit {coinsInPurse = 0}}  var playerOne: Player? = Player(coins: 100) println("coinsInPurse   :  \(playerOne!.coinsInPurse) coins")playerOne = nilprintln("PlayerOne has leftthe game")

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