Add a flushInterval configuration option

Ref: LIB-443

Analytics/Classes/Internal/SEGSegmentIntegration.m

@@ -119,7 +119,11 @@ - (id)initWithAnalytics:(SEGAnalytics *)analytics httpClient:(SEGHTTPClient *)ht
 
 - (void)setupFlushTimer
 {
-    self.flushTimer = [NSTimer scheduledTimerWithTimeInterval:30.0 target:self selector:@selector(flush) userInfo:nil repeats:YES];
+    self.flushTimer = [NSTimer scheduledTimerWithTimeInterval:self.configuration.flushInterval
+                                                       target:self
+                                                     selector:@selector(flush)
+                                                     userInfo:nil
+                                                      repeats:YES];
 }
 
 /*

Analytics/Classes/SEGAnalyticsConfiguration.h

@@ -61,6 +61,10 @@ typedef NSMutableURLRequest *_Nonnull (^SEGRequestFactory)(NSURL *_Nonnull);
  */
 @property (nonatomic, assign) NSUInteger flushAt;
 
+/**
+ * The amount of time to wait before each tick of the flush timer. Smaller values will make events delivered in a more real-time manner and also use more battery. `30` by default.
+ */
+@property (nonatomic, assign) NSTimeInterval flushInterval;
 
 /**
  * Whether the analytics client should automatically make a track call for application lifecycle events, such as "Application Installed", "Application Updated" and "Application Opened".

Analytics/Classes/SEGAnalyticsConfiguration.m

@@ -55,6 +55,7 @@ - (instancetype)init
         self.enableAdvertisingTracking = YES;
         self.shouldUseBluetooth = NO;
         self.flushAt = 20;
+        self.flushInterval = 30;
         _factories = [NSMutableArray array];
         Class applicationClass = NSClassFromString(@"UIApplication");
         if (applicationClass) {

AnalyticsTests/AnalyticsTests.swift

@@ -41,6 +41,7 @@ class AnalyticsTests: QuickSpec {
 
     it("initialized correctly") {
       expect(analytics.configuration.flushAt) == 20
+      expect(analytics.configuration.flushInterval) == 30
       expect(analytics.configuration.writeKey) == "QUI5ydwIGeFFTa1IvCBUhxL9PyW5B0jE"
       expect(analytics.configuration.shouldUseLocationServices) == false
       expect(analytics.configuration.enableAdvertisingTracking) == true
@@ -120,6 +121,29 @@ class AnalyticsTests: QuickSpec {
       let task = UIApplication.shared.beginBackgroundTask(expirationHandler: nil)
       UIApplication.shared.endBackgroundTask(task)
     }
+
+    it("flushes using flushTimer") {
+      let integration = analytics.test_integrationsManager()?.test_segmentIntegration()
+
+      analytics.track("test")
+
+      expect(integration?.test_flushTimer()).toEventuallyNot(beNil())
+      expect(integration?.test_batchRequest()).to(beNil())
+
+      integration?.test_flushTimer()?.fire()
+
+      expect(integration?.test_batchRequest()).toEventuallyNot(beNil())
+    }
+
+    it("respects flushInterval") {
+      let timer = analytics
+        .test_integrationsManager()?
+        .test_segmentIntegration()?
+        .test_flushTimer()
+
+      expect(timer).toNot(beNil())
+      expect(timer?.timeInterval) == config.flushInterval
+    }
   }
 
 }

AnalyticsTests/Utils/TestUtils.swift

@@ -58,6 +58,12 @@ extension SEGSegmentIntegration {
   func test_traits() -> [String: AnyObject]? {
     return self.value(forKey: "traits") as? [String: AnyObject]
   }
+  func test_flushTimer() -> Timer? {
+    return self.value(forKey: "flushTimer") as? Timer
+  }
+  func test_batchRequest() -> URLSessionUploadTask? {
+    return self.value(forKey: "batchRequest") as? URLSessionUploadTask
+  }
 }