Add support for SSL Pinning

Analytics/Classes/Internal/SEGHTTPClient.h

@@ -18,6 +18,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, strong) SEGRequestFactory requestFactory;
 @property (nonatomic, readonly) NSMutableDictionary<NSString *, NSURLSession *> *sessionsByWriteKey;
 @property (nonatomic, readonly) NSURLSession *genericSession;
+@property (nonatomic, weak)  id<NSURLSessionDelegate> httpSessionDelegate;
 
 + (SEGRequestFactory)defaultRequestFactory;
 + (NSString *)authorizationHeader:(NSString *)writeKey;

Analytics/Classes/Internal/SEGHTTPClient.m

@@ -51,7 +51,7 @@ - (NSURLSession *)sessionForWriteKey:(NSString *)writeKey
             @"Authorization" : [@"Basic " stringByAppendingString:[[self class] authorizationHeader:writeKey]],
             @"User-Agent" : [NSString stringWithFormat:@"analytics-ios/%@", [SEGAnalytics version]],
         };
-        session = [NSURLSession sessionWithConfiguration:config];
+        session = [NSURLSession sessionWithConfiguration:config delegate:self.httpSessionDelegate delegateQueue:NULL];
         self.sessionsByWriteKey[writeKey] = session;
     }
     return session;

Analytics/Classes/Internal/SEGSegmentIntegration.m

@@ -81,6 +81,7 @@ - (id)initWithAnalytics:(SEGAnalytics *)analytics httpClient:(SEGHTTPClient *)ht
         self.analytics = analytics;
         self.configuration = analytics.configuration;
         self.httpClient = httpClient;
+        self.httpClient.httpSessionDelegate = analytics.configuration.httpSessionDelegate;
         self.storage = storage;
         self.apiURL = [SEGMENT_API_BASE URLByAppendingPathComponent:@"import"];
         self.userId = [self getUserId];

Analytics/Classes/SEGAnalyticsConfiguration.h

@@ -166,4 +166,9 @@ typedef NSMutableURLRequest *_Nonnull (^SEGRequestFactory)(NSURL *_Nonnull);
  */
 @property (nonatomic, strong, nonnull) NSDictionary<NSString*, NSString*>* payloadFilters;
 
+/**
+ * An optional delegate that handles NSURLSessionDelegate callbacks
+ */
+@property (nonatomic, strong, nullable) id<NSURLSessionDelegate> httpSessionDelegate;
+
 @end

AnalyticsTests/AnalyticsTests.swift

@@ -47,6 +47,7 @@ class AnalyticsTests: QuickSpec {
       expect(analytics.configuration.shouldUseLocationServices) == false
       expect(analytics.configuration.enableAdvertisingTracking) == true
       expect(analytics.configuration.shouldUseBluetooth) == false
+      expect(analytics.configuration.httpSessionDelegate) == nil
       expect(analytics.getAnonymousId()).toNot(beNil())
     }