Question

I’m regularly getting some callbacks that I need to process on other thread, and I would like to queue those processing methods on one thread, so they would run in a order. I don’t want to use raw NSThread (because there’s too much work) and don’t wan to use GCD (because need to support iOS 3.1). Started to look at NSOperation but there’s a need to subclass, pass needed data and etc. Then started to think about runLoops… Anyway, what are the convenient ways for achieving the task?

Answer 1

NSOperation will be cleaner to set up than a run loop. You don’t say what your callbacks are. Are they functions? selectors? blocks? objects?

Your NSOperation subclass only needs to override main and provide a means to pass the callback to the operation.

@interface MyOperation : NSOperation
{
@private 
    CallbackType callback; // is e.g. a function pointer
    void* context;         // a parameter for the callback as an example
}
-(id) initWithCallback: (CallbackType) newCallback;
            andContext: (void*) newContext;
@end

@implementation MyOperation

-(id) initWithCallback: (CallbackType) newCallback
{
    self = [super init];
    if (self != nil)
    {
        callback = newCallback;
        context = newContext;
    }
    return self;
}

-(void) main
{
    callback(context);
}

@end