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by joshaber 5561 days ago
AppKit and UIKit aren't at all similar. And they aren't related. UIKit was written from the ground up for iOS and is based on Core Animation. AppKit was written by NeXSTEP and is based on software rendering with dirty rects.
2 comments
kenferry 5561 days ago
This argument seems strange to me.

UIKit was written, from the ground up, by people who either worked on AppKit or worked with AppKit, with full access to the AppKit source base. They share almost all design patterns, and some source code. UIKit is clearly based on AppKit.

Pervasive use of layers is indeed a difference. That's hardly the only thing interesting about either framework, though.

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joshaber 5561 days ago
Compare NSView vs. UIView. Or NSViewController vs. UIViewController. Or NSTableView vs. UITableView. NSButton vs. UIButton. Same names but very different design patterns and APIs.

I've worked on many iOS and Mac apps. I'm honestly not sure how anyone can claim AppKit and UIKit are essentially the same.

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kenferry 5561 days ago
What would you consider the essential Cocoa design patterns? I would point at the items listed at http://developer.apple.com/library/ios/#documentation/Cocoa/... . Delegation, notification, target action, the responder chain - these are all shared.

The frameworks are not identical, but to say they're not related… they only look wildly different if you're focusing in incredibly closely. If you consider .Net, or Java, or Rails, or GTK, or almost anything else, the differences between AppKit and UIKit are miniscule.

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ajg1977 5561 days ago
Nobody is saying that that they're not related. They clearly are (although the presence of other UI libraries does not affect any comparison of that relationship at all.

Your examples of delegates, responders, targets etc are concepts - and indeed UIKit and AppKit are both built around the same concepts.

The implementations of both is quite different however, to the point that porting something of complexity from UIKit to AppKit involves a lot of tedious changes - or worse: creation of abstraction layers if the codebase is to be maintained for both apps.

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scrod 5561 days ago
> AppKit and UIKit aren't at all similar. And they aren't related.

Actually, they're incredibly similar in terms of class hierarchy, design patterns (e.g., delegates, data sources, target/action for the most part), graphics principles (points vs pixels), use of various Foundation and CoreGraphics data structures, etc.

And yes, Core Animation works quite well with layer-backed views in AppKit, which is where it started.

It's easy to point out specific differences between these frameworks, but I think any developer who's already learned one would object to the underestimation of his/her intelligence that would be implied by comparing the subsequent difficulty in moving to the other with that of any other non-Apple platform SDK.

Perhaps you'd like to point out another SDK that is more similar to AppKit than UIKit?

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