[ios] swift 체험하기 #6 클래스2 & 옵셔널
import UIKit
var str = "Hello, playground"
class Person {
var name = ""
var age = 0
//default initialiazer
init() {
}
//initialize with parameters(custom initializer)
init(_ name:String, _ age:Int) {
self.name = name
self.age = age
}
convenience init(_ name:String) { // must be call other init
self.init(name, 1)
}
func printInfo() {
print("Name is \(name)")
print("Age is \(age)")
}
}
class BookInfo {
var title:String? //optional - initialize to 'nil', nil like null
var author:Person? //optional - initialize to 'nil'
}
var p = Person()
p.printInfo()
var p2 = Person("Someone")
p2.printInfo()
var my = Person("Test", 20)
my.printInfo()
var myBook = BookInfo()
myBook.title = "Swift"
myBook.author = my
print(myBook.title) //warning
if let myBookTitle = myBook.title { //no warning
print(myBookTitle)
}
if myBook.author != nil {
myBook.author!.printInfo() //! : using optional variable
}
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