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an0/NSObjectVSNSObjectProtocol.md

Last active August 29, 2015 14:26
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NSObject VS NSObjectProtocol
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NSObjectVSNSObjectProtocol.md

NSObjectProtocol is more general than NSObject and isEqual and hash are defined in NSObjectProtocol. Logically, we should inherit NSObjectProtocol from Equatable and Hashable.

Why not? Why instead extend NSObject to conform to Equatable and Hashable?

The current design causes problems like this:

if obj.delegate == self {

Binary operator '==' cannot be applied to operands of type 'XXXDelegate' and 'XXXDelegate'

because delegates are NSObjectProtocol not NSObject.

The only reason I can think of is if we use the alternative design NSObjectProtocol will become an protocol with Self or associated type requirement. But will it cause any negative effects? What are they?

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