On Jul 11, 2015, at 11:51 , Jens Alfke <j...@mooseyard.com> wrote:
>
> I think William asked how to implement a custom description, not how to print
> it.
Roland was pointing out that Swift uses the custom description for string
interpolation, which is the equivalent of using a “%@“ format string in Obj-C.
That doesn’t prevent William from using NSLog with a format string, but I think
it was worth noting that Swift has a native equivalent.
However, Roland got it slightly wrong, according to the documentation. This:
print (“\(myObj)”)
never uses debugDescription, only description. To use debugDescription (if it
exists, or description instead):
debugPrint (“\(myObj)”)
> The method is the same (for compatibility): description(). But since Swift is
> stricter about typing, you have to implement the Printing (sp?) protocol,
> which contains just that one method, to signal that your class has a custom
> description.
As Roland said, the protocol name changed in Swift 2, and it’s now
CustomStringConvertible or CustomDebugStringConvertible**. However, it’s not
about strict typing, but strictly indicating the behavior you’re intending to
provide (aka “conforming”).
** There are 3 other “Custom…” family protocols, but it doesn’t look they get
used for the print functions.
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