guard

var a : Int? = 100

var b : Int? = nil

 

func guardFunc001 () {

    guard let p1 = a else {

        print("p1 is nil")

        return

    }

    print("p1 = \(p1)")

}

 

func guardFunc002 () {

    guard let p1 = b else {

        print("p1 is nil")

        return

    }

    print("p1 = \(p1)")

}

 

guardFunc001() // resut : p1 = 100

guardFunc002() // resut : p1 is nil