Merge pull request ReactiveCocoa#29 from Lightricks/feature/racsubject-leak

RACSubject: avoid retaining the subscribers strongly in the disposable.

Author: barakwei

ReactiveObjC/RACSubject.m

@@ -61,8 +61,14 @@ - (RACDisposable *)subscribe:(id<RACSubscriber>)subscriber {
   @synchronized (subscribers) {
     [subscribers addObject:subscriber];
   }
-  
+
+  @rac_weakify(subscribers, subscriber);
   [disposable addDisposable:[RACDisposable disposableWithBlock:^{
+    @rac_strongify(subscribers, subscriber);
+    if (!subscribers || !subscriber) {
+      return;
+    }
+
     @synchronized (subscribers) {
       // Since newer subscribers are generally shorter-lived, search
       // starting from the end of the list.

ReactiveObjCTests/RACSubjectSpec.m

@@ -72,14 +72,28 @@ - (void)didSubscribeWithDisposable:(RACCompoundDisposable *)disposable {
   });
 
   qck_it(@"should dispose the paired disposable when a subscription terminates", ^{
-    RACSubject* subject = [RACSubject new];
-    RACTestSubscriber* subscriber = [RACTestSubscriber new];
+    RACSubject *subject = [RACSubject new];
+    RACTestSubscriber *subscriber = [RACTestSubscriber new];
 
     [[subject subscribe:subscriber] dispose];
 
     expect(@(subscriber.disposable.disposed)).to(beTruthy());
   });
 
+  qck_it(@"should release the subscriber after subject deallocation", ^{
+    __weak RACTestSubscriber *weakSubscriber;
+
+    @autoreleasepool {
+      RACTestSubscriber *subscriber = [RACTestSubscriber new];
+      weakSubscriber = subscriber;
+      RACSubject *subject = [RACSubject subject];
+
+      [subject subscribe:subscriber];
+    }
+
+    expect(weakSubscriber).to(beNil());
+  });
+
   qck_itBehavesLike(RACSubscriberExamples, ^{
     return @{
       RACSubscriberExampleSubscriber: subject,