runtime added application:openURL not fires - ios

Question

For some reason I develop static library for facebook connection.
For proper process authorizated URL appDelegate should have
- (BOOL)application:(UIApplication *)application
openURL:(NSURL *)url
sourceApplication:(NSString *)sourceApplication
annotation:(id)annotation
method.
So when I code it in appDelegate.mm file all works well, method invokes and facebook session become authorized.
But I have to add this method to delegate in runtime, so I use follow code:
{
NSString* methodDescription;
methodDescription = #"B#:####";
UIApplication* app = [UIApplication sharedApplication];
bool res = class_addMethod([app.delegate class], #selector(application:openURL:sourceApplication:annotation:), (IMP)applicationIMP, [methodDescription UTF8String]);
NSLog(#"Result of add method is %d", res);
}
//here is implementation of new method:
bool applicationIMP(id self, SEL _cmd, UIApplication *application, NSURL *url, NSString *sourceApplication, id annotation)
{
NSLog(#"Log from applicationIMP injected method");
return [[LibSocial sharedInstance] FacebookHandleOpenURL:url];
}
this code successfully adds method (I see this method when calls class_copyMethodList):
2013-02-04 23:02:00.704 LibSocialTest[38167:19a03] Mathod[0] is application:openURL:sourceApplication:annotation:
But Facebook SDK doesn't fire this method after authentication, and I got FBSessionState FBSessionStateClosedLoginFailed.
Why this method didn't fired?
Update:
Even if I replace normally implemented method with custom implementation at runtime, all works well and Facebook SDK fires new method implementation. But if I didn't code normally this method, but add it at runtime, it isn't fires.
Update2
If I add method to appDelegate class before instantiating UIApplication (in main.m file), then injected method works (even there are no default implementation of method in appDelegate.mm file), but if I inject method after UIApplication was created (so instance of appDelegate class was created too), then injection of method doesn't affect on already instantiated instances of class.