GSAppDelegate.m

//
//  GSAppDelegate.m
//  Fart
//
//  Created by John Heaton on 5/16/14.
//  Copyright (c) 2014 John Heaton. All rights reserved.
//

#import "GSAppDelegate.h"
#import <AFNetworking/AFNetworking.h>
#import <ReactiveCocoa/ReactiveCocoa.h>
#import <CoreServices/CoreServices.h>

static void FSCB(ConstFSEventStreamRef streamRef,
                 void *clientCallBackInfo,
                 size_t numEvents,
                 void *eventPaths,
                 const FSEventStreamEventFlags eventFlags[],
                 const FSEventStreamEventId eventIds[]) {

  // get the subscriber reference back
  id<RACSubscriber> s = (__bridge id<RACSubscriber>)(clientCallBackInfo);

  // get first path
  NSString *path = @(*(char **)eventPaths);

  // send tuple with path + flags
  [s sendNext:[RACTuple tupleWithObjects:path, @(*eventFlags), nil]];
}

@implementation GSAppDelegate

- (RACSignal *)watchPath:(NSString *)path {
  return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

    // create context with ref to this signal's subscriber
    FSEventStreamContext c;
    bzero(&c, sizeof(c));
    c.info = (__bridge void *)(subscriber);

    // create event stream
    FSEventStreamRef s =
    FSEventStreamCreate(NULL, FSCB, &c, (__bridge CFArrayRef)(@[ path ]), kFSEventStreamEventIdSinceNow, 0, kFSEventStreamCreateFlagFileEvents);

    // add to the current run loop and listen
    FSEventStreamScheduleWithRunLoop(s, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
    if(!FSEventStreamStart(s)) {
      // if it fails, remove from run loop and error
      FSEventStreamUnscheduleFromRunLoop(s, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
      [subscriber sendError:[NSError errorWithDomain:NSCocoaErrorDomain code:1 userInfo:@{ NSLocalizedFailureReasonErrorKey : @"Failed to start event stream" }]];
    }

    return [RACDisposable disposableWithBlock:^{
      // clean up
      FSEventStreamInvalidate(s);
      FSEventStreamStop(s);
      FSEventStreamRelease(s);
    }];
  }];
}

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
  // subscribe to signal
  [[self watchPath:@"/tmp"]
   subscribeNext:^(RACTuple *update) {
     NSLog(@"path: \'%@\', flags: 0x%x", update.first, [update.second unsignedIntValue]);
  }
   error:^(NSError *error) {
     NSLog(@"fail: %@", error);
  }];
}

@end