LocationController.m

@interface LocationController () <CLLocationManagerDelegate>

@property (nonatomic) CLLocationManager *locationManager;

@end

@implementation LocationController

- (RACSignal *)locationUpdate
{
    return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
        [self.locationManager startUpdatingLocation];

        [[self locationUpdated] subscribeNext:^(id x) {
            [subscriber sendNext:x];
            [subscriber sendCompleted];
        }];

        [[self locationUpdateError] subscribeError:^(NSError *error) {
            [subscriber sendError:error];
        }];

        return [RACDisposable disposableWithBlock:^{
            [self.locationManager stopUpdatingLocation];
        }];
    }];
}

- (RACSignal *)locationUpdated
{
    @weakify(self)
    return [[[[[self rac_signalForSelector:@selector(locationManager:didUpdateLocations:) fromProtocol:@protocol(CLLocationManagerDelegate)] map:^id(RACTuple *tuple) {
        NSArray *locations = tuple.second;
        return locations.lastObject;
    }] filter:^BOOL(CLLocation *location) {
        return !location.isStale;
    }] take:1] doCompleted:^{
        @strongify(self)
        [self.locationManager stopUpdatingLocation];
    }];
}

- (RACSignal *)locationUpdateError
{
    return [[[self rac_signalForSelector:@selector(locationManager:didFailWithError:) fromProtocol:@protocol(CLLocationManagerDelegate)] map:^id(RACTuple *tuple) {
        return tuple.second;
    }] take:1];
}