[swift] Optionals

Optionals A type that represents either a wrapped value or nil, the absence of a value. swift types can be optianl , which is indicated by appending ? to a type name The Optinal type is an enumeration with two cases none is equivalent to the nil literal some(Wrapped) stores a wrapped value. You can't use Optinal types like non-Optional types. It is necessary unwrapping the value of an Optional instance before using it in many context. Swift provides **sever

2020년 9월 7일
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