Day 9 – Structs Part Two

// initializers
// by default, structs use an initializer which requires us, at call time, to
// provide values for each property. However we can create our own.

struct User {
    var username: String
   
    init() {
        username = "Anonymous"
        print("Creating a new user...")
    }
}

// important to note: do not write methods before the initializer, and make
// sure all properties have a value by the time the initializer ends.

var myUser = User()
myUser.username
myUser.username = "newUsername"

// "self"
// the "self" keyword refers to the instance of the struct currently being used

struct Car {
    var model: String
   
    init(model: String) {
        print("This car's model is \(model)")
        self.model = model // model is the parameter, self.model the property
    }
}

var myCar = Car(model: "Tucson")

// lazy properties
// there might be some properties of a struct that take a lot of memory, or
// processing power. for this reason, if we add the keyword 'lazy' swift will
// only create that property when it's first accessed.

struct Dog {
    var name: String
    lazy var car = Car(model: "Doggydog")
   
    init(name: String) {
        self.name = name
    }
}

// static properties and methods
// so far, all properties and methods belonged to the particular instances of
// the struct made. But what about making one for the struct itself, shared
// among all instances? that's what static properties are

struct Student {
    static var classSize = 0
    var name: String
   
    init(name: String) {
        self.name = name
        Student.classSize += 1
    }
}

// given it's static we need to call it using Student.classSize (it belongs to
// the struct)

// private properties
// we can make it so that properties of a struct cannot be read from outside the
// struct's methods itself.

struct Person {
    private var id: String
   
    init(id: String) {
        self.id = id
    }
   
    func identify() -> String {
        return "This person's ID is \(id)."
    }
}

var myPerson = Person(id: "12345")
myPerson.identify()

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