Fix GCD mutual dependency (#785)

Author: Fathy Boundjadj

Analytics/Classes/Internal/SEGSegmentIntegration.m

@@ -106,26 +106,18 @@ - (id)initWithAnalytics:(SEGAnalytics *)analytics httpClient:(SEGHTTPClient *)ht
             [self trackAttributionData:self.configuration.trackAttributionData];
         }];
 
-        if ([NSThread isMainThread]) {
-            [self setupFlushTimer];
-        } else {
-            dispatch_sync(dispatch_get_main_queue(), ^{
-                [self setupFlushTimer];
-            });
-        }
+        self.flushTimer = [NSTimer timerWithTimeInterval:self.configuration.flushInterval
+                                                  target:self
+                                                selector:@selector(flush)
+                                                userInfo:nil
+                                                 repeats:YES];
+        
+        [NSRunLoop.mainRunLoop addTimer:self.flushTimer
+                                forMode:NSDefaultRunLoopMode];
     }
     return self;
 }
 
-- (void)setupFlushTimer
-{
-    self.flushTimer = [NSTimer scheduledTimerWithTimeInterval:self.configuration.flushInterval
-                                                       target:self
-                                                     selector:@selector(flush)
-                                                     userInfo:nil
-                                                      repeats:YES];
-}
-
 /*
  * There is an iOS bug that causes instances of the CTTelephonyNetworkInfo class to
  * sometimes get notifications after they have been deallocated.