iphone ios running in separate thread

What is the best way to run code on a separate thread? Is it:

[NSThread detachNewThreadSelector: @selector(doStuff) toTarget:self withObject:NULL];

Or:

	NSOperationQueue *queue = [NSOperationQueue new];
NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self
																		selector:@selector(doStuff:)
																		  object:nil;
[queue addOperation:operation];
[operation release];
[queue release];

I've been doing the second way but the Wesley Cookbook I've been reading uses the first.

In my opinion, the best way is with libdispatch, aka Grand Central Dispatch (GCD). It limits you to iOS 4 and greater, but it's just so simple and easy to use. The code to do some processing on a background thread and then do something with the results in the main run loop is incredibly easy and compact:

dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    // Add code here to do background processing
    //
    //
    dispatch_async( dispatch_get_main_queue(), ^{
        // Add code here to update the UI/send notifications based on the
        // results of the background processing
    });
});

If you haven't done so already, check out the videos from WWDC 2010 on libdispatch/GCD/blocks.

The best way for the multithreading in iOS is using GCD (Grand Central Dispatch).

//creates a queue.

dispatch_queue_t myQueue = dispatch_queue_create("unique_queue_name", NULL);

dispatch_async(myQueue, ^{
    //stuffs to do in background thread
    dispatch_async(dispatch_get_main_queue(), ^{
    //stuffs to do in foreground thread, mostly UI updates
    });
});

I would try all the techniques people have posted and see which is the fastest, but I think this is the best way to do it.

[self performSelectorInBackground:@selector(BackgroundMethod) withObject:nil];

I have added a category on NSThread that will let you execute threads in blocks with ease. You can copy the code from here.

https://medium.com/@umairhassanbaig/ios-how-to-perform-a-background-thread-and-main-thread-with-ease-11f5138ba380