可选类型的本质
2022-03-22 本文已影响0人
aven_kang
var age: Int? = 10
age = 20
age = nil
var age1 : Optional<Int> = Optional.some(10)
age1 = Optional.some(20)
age1 = Optional.none
var age: Int? = 10
age = 20
age = nil
var age1 : Optional<Int> = Optional.some(10)
age1 = Optional.some(20)
age1 = Optional.none