ARC Semantic Issue: No visible @interface for Class declares the selector

问题

Pretty basic stuff but i am unable to troubleshoot where the problem is. In my project, i have a class named "TheFeedStore" with following two methods:

- (BOOL)hasItemBeenRead:(RSSItem *)item
{
   ............
}

- (void)markItemAsRead:(RSSItem *)item
{
  .........
}

I am using the following class method so other classes can access these methods using it:

+ (TheFeedStore *) sharedStore
{
    static TheFeedStore *feedStore = nil;

    if (!feedStore) {
        feedStore = [[TheFeedStore alloc] init];
    }
    return feedStore;
}

In one of my another class, i can easily access the above methods by writing

if ([[TheFeedStore sharedStore] hasItemBeenRead:item])

[[TheFeedStore sharedStore] markItemAsRead:entry];

But in another class if i try to access these methods in a similar manner, i get the error "No visible @interface for 'TheFeedStore' declares the selector 'hasItemBeenRead:"

1) I have imported TheFeedStore.h file in the classes from i am accessing these methods of TheFeedStore class.

2) I have checked like 10 times and there is no typo.

3) The methods i am accessing are also declared in the header file of TheFeedStore.h

UPDATE: Just to check, i have declared another test method in TheFeedStore.h, same result, one class can access the newly created method while rest of the three classes cannot.

UPDATE: I have tried creating more methods in the TheFeedStore.h just for troubleshooting this issue. The new methods are also not accessible from the other classes. But if the return type of these new methods is (RSSChannel*) which is another model class in my project, than they become accessible. If their return type is other than some class like (void) and (BOOL) then they are not accessible. Here is my TheFeedStore.h https://gist.github.com/jessicamoore112/5558473

回答1:

You have said that you are using @class instead of #import in your header files, the methods that you are trying to access are declared in the header files and there are no typos of any kind.

In such cases, usually no body points this issue but i am going to do it anyway because i have faced such issues many times. You have probably created many copies of your project to work on each functionality and also keeping a working project.

When you do this, sometimes Xcode is still using the older copies of few files. That means it is still using the older copy of the TheFeedStore.h when the methods you are trying to access were not declared by you.

How to solve this problem is very simple. Go to the file from which you are trying to access the methods and the files in which these methods are declared.

In the Utilities section on the right hand side, check the location and full path under "Identity and Type" area.

First check the names of the project, if it is different from the project name that you are working on, that means Xcode is still pulling the old copies of the files from the previous revision of your project. See the blue arrows where the project name is 13SampleMoreRequests in my case.

If this name is same as your project name, then my answer does not solve your problem. If its different, you should use the new copies of the file by browsing the new location using the sign that is pointed out by red arrow.

Once you browse and use the new files, your problem will be solved and you will be able to access the methods. If you still can't, copy these files, delete from the project and then add them again and you won't face this problem.

Hope this helps!

回答2:

Cyclical imports, e.g. A.h imports B.h while also B.h imports A.h is the most common problem.

In C, cyclical imports won't work and one of the imports will be silently ignored. Make sure you are not having a cyclical import. If you do, solve it (e.g. using forward declarations).

Import problems can be also easily inspected if you generate the preprocessed output (you can find it in one of the Xcode menus).

回答3:

That might sound silly, but I have similar cases once in a while and sometimes just simple quitting and starting xcode helps, it tends to stuck sometimes. Also, sometimes cleaning the project helps. 'Cause I have very similar to yours singleton code and it works fine.

回答4:

Guys I had encountered the exact same issues. After some searching on SO and the search engine I was able to solve it.

In my Case I have four files:

RadioStation.h
RadioStation.m
ViewController.h
ViewController.m

My mistake was to place all my methods in RadioStation.m and only put my variables on radioStation.h So when I import radioSation.h on my ViewController.m and try to define methods for button-click on my app that's where the problems started. I got the error/warnings "ARC Semantic Issue: No visible @interface for Class declares the selector" every time I built or ran the app simulator.

My Solution was to go back to RadioStation.h file and just declare all my methods there. Since they were already defined on RadioStation.m I was good to go.

So make sure you have properly declared your methods on the file that is going to be imported on your viewControllers. Hope that helps.