How to read keychain item

Question

I would like to read a keychain item through Objective-C, I found and read the Apple Documentation

It shows example code, however after properly linking the required frameworks (SystemConfiguration.framework and Security.framework), it is still not clear to me, how I can make it work.

I am also figuring out how to use SSKeychain Wrapper, but I get unrecognized selector sent to class upon calling it during runtime:

-(IBAction) button:(id)sender
{
    NSArray *keychainAccounts = [[self class] allAccounts];
    NSLog(@"Keychain accounts are: %@", keychainAccounts);
}

Thanks a lot.