crash in `[NSApp run]` when delegate is not referenced anymore - objective-c

Question

This is the code:
#interface AppDelegate : NSObject <NSApplicationDelegate>
#end
#implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
printf("My app delegate: finish launching\n");
}
#end
int main(int argc, char *argv[])
{
#autoreleasepool
{
[NSApplication sharedApplication];
[NSApp setDelegate:[[AppDelegate alloc] init]];
[NSApp run];
}
}
It crashes in [NSApp run] but I don't really see what I'm missing. If I add an [NSApp finishLaunching] before the run, it crashes in there.
If I don't set the delegate, it doesn't crash.
If I reference the delegate before, it works fine:
AppDelegate* appDelegate = [[AppDelegate alloc] init];
[NSApp setDelegate:appDelegate];
So I guess it releases the delegate immediately in the first version because of ARC and because the delegate is probably only a weak reference, right? But how are you supposed to do the same code otherwise?

Answer 1

Yes you guess right, NSApplication don't retain the delegate, (weak reference with ARC).
So you can just build the main.m file with -fno-objc-arc with you current code :
int main(int argc, char *argv[])
{
#autoreleasepool
{
[NSApplication sharedApplication];
[NSApp setDelegate:[[AppDelegate alloc] init]];
[NSApp finishLaunching];
[NSApp run];
}
}
or set you AppDelegate static in main.m, for example, and build with ARC
static AppDelegate* _appDelegate;
int main(int argc, char *argv[])
{
#autoreleasepool
{
_appDelegate = [[AppDelegate alloc] init];
[NSApplication sharedApplication];
[NSApp setDelegate:_appDelegate];
[NSApp run];
}
}