CODEWITHSUNDEEP
iphoneobjective-cprotocols
Sinba
Sinba

Reputation: 271

Protocol error. Cannot find protocol declaration

We have error: cannot find protocol declaration for 'ClassWhichUseMainScene' [3]

We created file: Protocol.h

#import "ScoreSystem.h"
#import "OtherSystem"
#import "OtherSystem2"

@class ScoreSystem;

@protocol SceneDelegate <NSObject>
@property (nonatomic, readonly,retain) ScoreSystem* score;
@property (nonatomic, readonly,retain) OtherSystem* system;
@property (nonatomic, readonly,retain) OtherSystem2* system2;

@end

And use in ScoreSystem.h

#import "Protocol.h"
#import "OtherSystem"
#import "OtherSystem2"

@interface ScoreSystem: NSObject <SceneDelegate> 
{
OtherSystem* system;
OtherSystem2* system2;
}

In ScoreSystem we want use just OtherSystem and OtherSystem2 objects. In OtherSystem use ScoreSystem and OtherSystem2, etc. We want create universal protocol for all system.

Upvotes: 1

Views: 1687

Answers (2)

A R
A R

Reputation: 461

Mine Problem resolved with simple import statement

#import "ProtocolContainingFile.h"

Upvotes: 0

JeremyP
JeremyP

Reputation: 86691

You have a circular dependency between your two header files (each imports the other). Do not import ScoreSystem.h in Protocol.h, the @class forward declaration is enough. The same goes for your other two imports.

As a general rule I avoid including class header files in other class header files - I just use @class everywhere and import the headers in the implementation files.

Upvotes: 4

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