Monday, June 29, 2020

as, as?, and as! in Swift

Ole Begemann:

as? and as! perform downcasting at runtime.


as? and as! are the same operation, the only difference being that as! force-unwraps its result.


In contrast, as coerces a value to a type at compile time.


A syntactic nuance: when using as in pattern matching contexts, the check is performed at runtime (it has to be).


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