Add podspec and fix iOS database null pointer

Firestack.podspec

@@ -1,61 +1,28 @@
 require 'json'
-package = JSON.parse(File.read('package.json'))
-version = package["version"]
-repo = package['repository']
-author = package['author']
 
-all_pods = [      
-  'FirebaseAnalytics', 'FirebaseAuth', 'FirebaseRemoteConfig',
-  'FirebaseDatabase', 'FirebaseStorage', 'FirebaseInstanceID',
-  'GoogleInterchangeUtilities', 'GoogleIPhoneUtilities',
-  'GoogleNetworkingUtilities', 'GoogleParsingUtilities',
-  'GoogleSymbolUtilities'
-]
+package = JSON.parse(File.read('package.json'))
 
 Pod::Spec.new do |s|
-
-  s.name         = "Firestack"
-  s.version      = version
-  s.summary      = "Firestack makes working with Firebase v3 easy"
-
-  s.description  = <<-DESC
-  Wanna integrate firebase into your app using React Native?
-                   DESC
-
-  s.homepage     = "http://fullstackreact.com"
-
-  s.license      = { :type => "MIT", :file => "LICENSE" }
-  s.author             = { "Ari Lerner" => author }
-  s.social_media_url   = 'http://twitter.com/fullstackio'
-
-  #  When using multiple platforms
-  s.ios.deployment_target = "8.0"
-  # s.osx.deployment_target = "10.7"
-  # s.watchos.deployment_target = "2.0"
-  # s.tvos.deployment_target = "9.0"
-
-  s.source = { :git => repo['url'], :tag => "v#{version}" }
-  s.public_header_files = "ios/Firestack/*.h"
-
-  s.source_files   = 'ios/Firestack/*.{h,m}'
-  s.preserve_paths = 'README.md', 'package.json', '*.js'
-
-  s.ios.frameworks = [
-    'CFNetwork', 'Security', 'SystemConfiguration'
-  ]
-  s.ios.libraries = ['icucore', 'c++', 'sqlite3', 'z']
-
-  s.xcconfig = {
-    'HEADER_SEARCH_PATHS' => [
-        "$(inherited)", 
-        "${SRCROOT}/../../React/**", 
-        "${SRCROOT}/../../node_modules/react-native/**"
-      ].join(' '),
-    'FRAMEWORK_SEARCH_PATHS' => [
-        "$(inherited)", 
-        "${PODS_ROOT}/Firebase/**",
-        "${PODS_ROOT}/FirebaseStorage/**",
-      ].join(' '),
-    'OTHER_LDFLAGS' => '$(inherited) -ObjC'
-  }
-end
+  s.name                = "Firestack"
+  s.version             = package["version"]
+  s.summary             = package["description"]
+  s.description         = <<-DESC
+                            Wanna integrate firebase into your app using React Native?
+                          DESC
+  s.homepage            = "http://fullstackreact.com"
+  s.license             = package['license']
+  s.author              = "Ari Lerner"
+  s.source              = { :git => "https://github.com/fullstackreact/react-native-firestack.git", :tag => "v#{s.version}" }
+  s.social_media_url    = 'http://twitter.com/fullstackio'
+  s.platform            = :ios, "8.0"
+  s.header_dir          = 'ios/Firestack'
+  s.preserve_paths      = 'README.md', 'package.json', '*.js'
+  s.source_files        = 'ios/Firestack/*.{h,m}'
+  s.dependency          'React'
+  s.dependency          'Firebase/Auth'
+  s.dependency          'Firebase/Core'
+  s.dependency          'Firebase/Database'
+  s.dependency          'Firebase/Messaging'
+  s.dependency          'Firebase/RemoteConfig'
+  s.dependency          'Firebase/Storage'
+end

ios/Firestack/FirestackDatabase.m

@@ -593,8 +593,11 @@ - (id) init
                   callback:(RCTResponseSenderBlock) callback)
 {
     NSString *key = [self getDBListenerKey:path withModifiers:modifiersString];
+    NSArray *listenerKeys;
     FirestackDBReference *ref = [_dbReferences objectForKey:key];
-    if (ref != nil) {
+    if (ref == nil) {
+        listenerKeys = @[];
+    } else {
         if (eventName == nil || [eventName isEqualToString:@""]) {
             [ref cleanup];
             [_dbReferences removeObjectForKey:key];
@@ -604,12 +607,13 @@ - (id) init
                 [_dbReferences removeObjectForKey:key];
             }
         }
+        listenerKeys = [ref listenerKeys];
     }
     callback(@[[NSNull null], @{
                    @"result": @"success",
                    @"handle": path,
                    @"modifiersString": modifiersString,
-                   @"remainingListeners": [ref listenerKeys],
+                   @"remainingListeners": listenerKeys,
                    }]);
 }