From 6f61b5437eaf425e073309f7252c8fa5ea908311 Mon Sep 17 00:00:00 2001
From: Nikita Lutsenko <nlutsenko@me.com>
Date: Thu, 12 Aug 2021 16:41:46 -0700
Subject: [PATCH] Guard potential unavailability of
 NSStreamNetworkServiceTypeCallSignaling.

---
 SocketRocket/Internal/Utilities/SRURLUtilities.m | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/SocketRocket/Internal/Utilities/SRURLUtilities.m b/SocketRocket/Internal/Utilities/SRURLUtilities.m
index 84585dad6..2f66d8d93 100644
--- a/SocketRocket/Internal/Utilities/SRURLUtilities.m
+++ b/SocketRocket/Internal/Utilities/SRURLUtilities.m
@@ -68,9 +68,11 @@ extern BOOL SRURLRequiresSSL(NSURL *url)
         case NSURLNetworkServiceTypeVoice:
             networkServiceType = NSStreamNetworkServiceTypeVoice;
             break;
-        case NSURLNetworkServiceTypeCallSignaling:
-            networkServiceType = NSStreamNetworkServiceTypeCallSignaling;
-            break;
+        case NSURLNetworkServiceTypeCallSignaling: {
+            if (@available(iOS 10.0, tvOS 10.0, macOS 10.12, *)) {
+                networkServiceType = NSStreamNetworkServiceTypeCallSignaling;
+            }
+        } break;
     }
     return networkServiceType;
 }