Merge pull request google#1 from LeoNatan/fix-further-swizzling-woes

Fix further NSURLSession swizzling woes

Author: LeoNatan

EarlGrey/Additions/NSURLSession+GREYAdditions.m

@@ -54,19 +54,21 @@ - (NSURLSessionDataTask *)greyswizzled_dataTaskWithRequest:(NSURLRequest *)reque
   // Swizzle the session delegate class if not yet done.
   id delegate = self.delegate;
   SEL originalSel = @selector(URLSession:task:didCompleteWithError:);
-  Class delegateClass =
-      [[delegate forwardingTargetForSelector:originalSel] class] ?: [delegate class];
-
+  // This is to solve issues where there is a proxy delegate instead of the original instance (e.g. TrustKit, New Relic).
+  // It responds YES to `respondsToSelector:` but `class_getInstanceMethod` returns nil.
+  // We attempt to follow the forwarding targets for the selector, if any exists.
+  id nextForwardingDelegate = nil;
+  while((nextForwardingDelegate = [delegate forwardingTargetForSelector:originalSel]) != nil)
+  {
+    delegate = nextForwardingDelegate;
+  }
+  Class delegateClass = [delegate class];
+  
   if (![delegateClass instancesRespondToSelector:swizzledSel]) {
-    SEL originalSel = @selector(URLSession:task:didCompleteWithError:);
     // If delegate does not exists or delegate does not implement the delegate method, then this
     // request need not be tracked as its completion/failure does not trigger any delegate
     // callbacks.
     if ([delegate respondsToSelector:originalSel]) {
-      // This is to solve issues where there is a proxy delegate instead of the original instance (e.g. TrustKit).
-      // It responds YES to `respondsToSelector:` but `class_getInstanceMethod` returns nil.
-      // We attempt to take the forwarding target for the selector, if it exists.
-      delegateClass = [[delegate forwardingTargetForSelector:originalSel] class] ?: delegateClass;
       Class selfClass = [self class];
       // Double-checked locking to prevent multiple swizzling attempts of the same class.
       @synchronized(selfClass) {