ReactiveCocoa: How to initialize a RACScheduler with a serially executing GCD queue.

RACSerialScheduler.m

@interface SerialScheduler () 
@property (nonatomic, strong) RACScheduler *serialScheduler;
@end
 
@implementation SerialScheduler
 
/**
* This scheduler executes signals one a 1-by-1 basis.
* Use it with ReactiveCocoa when you want to handle signal execution serially.
*/
- (RACScheduler *)serialScheduler
{
    if(!_serialScheduler){
        _serialScheduler = [[RACTargetQueueScheduler alloc] initWithName:@"QueueName" 
                                                             targetQueue:dispatch_queue_create("QueueName", DISPATCH_QUEUE_SERIAL)];
    }
    return _serialScheduler;
}
 
@end

Usage:

...
    @weakify(self)
    return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
        @strongify(self)
        return [self.serialScheduler schedule:^{
            // do something
        }];
    }]
...