How do I determine what protocols a class conforms to in swift?

Question

In objective-c, you can always check a class's protocols through its public headers. But if you have a class in swift, how do you know what protocols it conforms to? Is this even possible?

(Yes, I realize Apple's documentation lists the protocols it conforms to, but that doesn't seem like a real solution, since you might be working with a private framework or have some other theoretical reason for wanting to know an object's protocols.)

Also, yes, I know you can check for a specific protocol using the technique outlined here: https://stackoverflow.com/a/37351027/18961

You can use 'is' or 'as' to verify the conformance (go to: Checking for Protocol Conformance): developer.apple.com/library/ios/documentation/Swift/Conceptual/… — Duyen-Hoa
– Duyen-Hoa, Commented Jun 14, 2016 at 20:31

Paul Cantrell · Accepted Answer · 2016-06-15 20:34:28Z

2

In Xcode, you can command-click on any Swift type to get a header-like view of its public interface, including protocol conformances added in both the original definition and in extensions.

This doesn’t show protocol conformances added by libraries outside the defining library, e.g. if you command-click String you won’t see your own extension String: MyFunkyProtocol. But I think it is essentially the header-file-like thing you’re looking for.

For the Swift standard lib, http://swiftdoc.org/ is a nice reference.

answered Jun 15, 2016 at 20:34

Paul Cantrell

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2 Comments

livingtech Over a year ago

What is the specific menu option to see this public interface? It's possible I'm just not seeing it.

Paul Cantrell Over a year ago

Right click on text in editor, “Jump to Definition.”

Jim · Accepted Answer · 2016-06-14 21:49:39Z

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I don't believe you can do it without leaning on the Objective-C runtime. Import ObjectiveC and use the class_copyProtocolList() function.

answered Jun 14, 2016 at 21:49

Jim

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2 Comments

livingtech Over a year ago

This was my understanding too, but I was hoping there was another way.

Paul Cantrell Over a year ago

This only works for subclasses of NSObject conforming to @objc protocols.

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