옵셔널 체이닝

/**
 옵셔널 체이닝
 
 */
class Dog{
    var name: String?
    var weight: Int?
    func sit(){
        print("앉았습니다.")
    }
}

var choco:Dog? = Dog()

choco?.name = "초코"
print(choco?.name)
if let name = choco?.name {
    print(name)
}
choco?.sit()