Question

My Application structure is as follows,
the core part is written in C++ and using thread heavily, and i am developing UI in Objective C on top of it,
if i don’t execute the thread it works fine, but i can’t disable, stop thread, UI is crashing randomly in the log i could see , following message

__NSAutoreleaseNoPool(): Object 0x350270 of class NSCFString autoreleased with no pool in place - just leaking

Similar messages coming more then once,
by googling come to know, i need to set NSAutoReleasePool to get rid of it, but how its possible to integrate the same with C++ code.

Edit: Core lib will be activated from UI , hence i suppose, its safe to say UI is running in the main thread, Lib is creating/terminating thread without notifying UI,
in this case, can i call AutoReleasePool in the UI

Can anyone guide me?

Answer 1

See these docs for what you should know about multithreading with Cocoa: http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Multithreading/ThreadSafetySummary/ThreadSafetySummary.html

It’s OK to design your app like you have, but two things should be kept in mind:

1. Life is simplest (and sometimes necessary) when UI controls like views (AppKit or UIKit) are manipulated on the main thread. You can use Foundation objects and some AppKit/UIKit objects on background threads, and some Foundation objects can be used from multiple threads.
2. If you’re using any Cocoa objects at all in background threads, you’ll need to set up autorelease pools on those threads.

Like so:

- (void)backgroundThreadStart 
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    // do stuff

    [pool release];
}

That will fix your console errors, but you might have other issues that led to the actual crashing you were seeing.