OptionalChaining.swift

struct Processor {
    var modelNumber: Int
    init() {
        self.modelNumber = 21043
    }
}

struct Computer {
    var processor: Processor?
    init(processor: Processor?) {
        self.processor = processor
    }
}

let myComputer = Computer(processor: Processor())

if let modelNumber = myComputer.processor?.modelNumber {
    print("The model number of the processor is \(modelNumber)")
} else {
    print("Seems like you need a processor for your computer")
}