Swift Protocols, Arrays, and Casting
But an EmailMessage is a NodeRepresentedObject, so it ought to work just fine.
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The best way I’ve found to deal with this is to map it. […] That seems crazy. I’m using map to create an array whose members are absolutely identical to the original array.
It’s not a type-check. The in-memory representation is different. It has to allocate a new array with the new values.
Non-@objc protocols use a virtual function table (called a protocol witness table) rather than message-passing.
This means that objects typed as EmailMessage have a different table pointer than those typed as NodeRepresentedObject.
I’d argue that, instead, there shouldn’t be a hidden performance gotcha.
That would be nice, but the only way to solve this without a new array basically requires all protocols to use message-passing
Message passing is a performance gotcha :P
But barely. We can write fast apps in Objective-C.
Yeah, but you should be able to write faster ones in Swift.
Except for when I have to make an exact copy of an array to satisfy the type system.
