ios - Why can [SomeClass class] return null in main.m -

i trying make ios app without using xibs or storyboards. main.m looks this:

int main(int argc, char *argv[]) {     nsautoreleasepool * pool = [[nsautoreleasepool alloc] init];     int retval = uiapplicationmain(argc, argv, nil, nsstringfromclass([appdelegate class]));     [pool release];     return retval; } 

if check value of [appdelegate class] (null). question is, why? if check [nsstring class] or other class standard library performs normally. thought file not in compile sources list, it's there. problem occurs in 1 project.

check if have initialized assigned controller window's root controller in - (bool)application:(uiapplication *)application didfinishlaunchingwithoptions:(nsdictionary *)launchoptions.

check out this answer.