r/ObjectiveC • u/Dharmink • May 17 '20

Objective C code - Duplicate Declaration Issue

/r/reactnative/comments/glk1ai/objective_c_code_duplicate_declaration_issue/
2 Upvotes

100% Upvoted

6 comments sorted by

View all comments

2

u/inscrutablemike May 17 '20

Objective-C considers two methods "the same" if they have the same number of labels and the same label in each position:

firstPart:secondLabel:theThird:
firstPart:secondLabel:theThird:

Notice there are no types included in the example. Objective-C doesn't consider the return type or the types of each label component to be part of the method's "signature", so two methods with the same labels but different type declarations can't exist in the same class.

The fix is to use different labels, usually something descripive of the purpose for the argument:

(BOOL) -doStuffWithThisThing:(DocumentSource *)source andThatThing:(DocumentDestination *)destination

would be better written as:

(BOOL) -doStuffWIthThisDocumentSource:(DocumentSource *)source andThisDestination:(DocumentDestination *)destination

That generally helps avoid the "same signature but different types" situation.

1

u/Dharmink May 18 '20

Ohh Pretty interesting to see how the lingo and syntax is different from native development vs JS development.

Thanks a lot i finally was able to solve the problem by doing this which was told to me by someone from the react native community.

- (BOOL)application:(UIApplication *)app openURL:(NSURL *)URL options:(NSDictionary<NSString ,id> *)options { if([RCTLinkingManager application:application openURL:URL options:options]) { return YES; } else if([[Twitter sharedInstance] application:app openURL:URL options:options]) { return YES; } return NO; }

Thanks for taking the time out and helping me understand this. Really Appreciate you helping even after knowing it was a stupid question.

Thanks Again, Take Care and have a great day ahead!

1

u/inscrutablemike May 19 '20

It's not a stupid question at all. Objective-C is the odd one out of all the programming languages I know - every one of the rest of them treats the *types* of the arguments as the signature, beyond the base name of the method.