Compiler errors with dumped headers when creating a Cydia Tweak with Theos

Question

I'm trying to write a tweak for an app on the iPhone. I have a good background in objective C and iPhone dev, but I've never done any Cydia jailbreak tweaks, save for a few tutorials on tweaks using rpetrich's dumped headers. I'm looking to use PoedCrackMod to decrypt, class-dump-z to get the headers, and then theos/logos to patch the cracked app.

I've gone ahead and run PoedCrackMod to decrypt the app. This yields me a .ipa file which I can then extract to get the .app file, which contains the actual application binary.

I can than use

class-dump-z -k -k -H -g -o ~/dumped_headers/ Foo

to go ahead and get a directory of headers files. I copy these headers to $THEOS/include/Foo. (Should I be using the -g option [Display exported classes only] here, or can I hook non-exported classes as well?)

At this point, I should be able to create a tweak.xm file that looks something like this:

#import <Foo/Foo.h>

and for reference the makefile looks like:

include theos/makefiles/common.mk

TWEAK_NAME = FooTweak
FooTweak_FILES = Tweak.xm

include $(THEOS_MAKE_PATH)/tweak.mk

When I go ahead and try to compile my Tweak (which at this point should do nothing), I come up with all sorts of duplicate declaration errors. Is this normal, or am I doing something wrong?

If it is normal, how do I go about correcting this? I've tried commenting out duplicate declarations, in which case I can get it to compile. I've inserted 20+ hooks that create UIAlertViews when the method is called, but none of them ever seem to trigger- leading me to believe that I'm not hooking methods that aren't being called, but that I'm either making a mistake in dumping the headers or importing the headers into my tweak?

Does anyone have any insights on what I may be doing wrong?

Answer 1

Do not use #import <Foo/Foo.h>

Instead

[File] tweak.xm:

#import <substrate.h>

@interface FooToBeHookedHeader : NSObject {} // We take NSObject here as to avoid any errors.
- (void)fooMethod1; // Only put the methods you are hooking
- (void)fooInheritedMethod; // Inherited method (if hooking) as we are using NSObject up there :)
@end

%hook FooToBeHookedHeader
- (void)fooMethod1 {
// Do hooking stuff
} 
- (void)fooInheritedMethod {
// Do hooking stuff
}
%end

// Include any instance variables which you are modifying if any :)
// ~ SuperDev

Also include the identifier of the App/Framework being hooked in your FooTweak.plist