replaced hardcoded server path with cmdline arg

The host and port of the remote server can be specified via command line argument to xcodebuild.

src/objective-c/tests/InteropTestsLocalCleartext.m

@@ -36,7 +36,11 @@
 
 #import "InteropTests.h"
 
-static NSString * const kLocalCleartextHost = @"localhost:5050";
+// The server address is derived from preprocessor macro, which is
+// in turn derived from environment variable of the same name.
+#define NSStringize_helper(x) #x
+#define NSStringize(x) @NSStringize_helper(x)
+static NSString * const kLocalCleartextHost = NSStringize(HOST_PORT_LOCAL);
 
 // The Protocol Buffers encoding overhead of local interop server. Acquired
 // by experiment. Adjust this when server's proto file changes.

src/objective-c/tests/InteropTestsLocalSSL.m

@@ -35,8 +35,11 @@
 #import <GRPCClient/internal_testing/GRPCCall+InternalTests.h>
 
 #import "InteropTests.h"
-
-static NSString * const kLocalSSLHost = @"localhost:5051";
+// The server address is derived from preprocessor macro, which is
+// in turn derived from environment variable of the same name.
+#define NSStringize_helper(x) #x
+#define NSStringize(x) @NSStringize_helper(x)
+static NSString * const kLocalSSLHost = NSStringize(HOST_PORT_LOCALSSL);
 
 // The Protocol Buffers encoding overhead of local interop server. Acquired
 // by experiment. Adjust this when server's proto file changes.

src/objective-c/tests/InteropTestsRemote.m

@@ -36,7 +36,11 @@
 
 #import "InteropTests.h"
 
-static NSString * const kRemoteSSLHost = @"grpc-test.sandbox.googleapis.com";
+// The server address is derived from preprocessor macro, which is
+// in turn derived from environment variable of the same name.
+#define NSStringize_helper(x) #x
+#define NSStringize(x) @NSStringize_helper(x)
+static NSString * const kRemoteSSLHost = NSStringize(HOST_PORT_REMOTE);
 
 // The Protocol Buffers encoding overhead of remote interop server. Acquired
 // by experiment. Adjust this when server's proto file changes.

src/objective-c/tests/InteropTestsRemoteWithCronet/InteropTestsRemoteWithCronet.m

@@ -39,7 +39,12 @@
 
 #import "InteropTests.h"
 
-static NSString * const kRemoteSSLHost = @"grpc-test.sandbox.googleapis.com";
+// The server address is derived from preprocessor macro, which is
+// in turn derived from environment variable of the same name.
+#define NSStringize_helper(x) #x
+#define NSStringize(x) @NSStringize_helper(x)
+static NSString * const kRemoteSSLHost = NSStringize(HOST_PORT_REMOTE);
+
 
 // The Protocol Buffers encoding overhead of remote interop server. Acquired
 // by experiment. Adjust this when server's proto file changes.

src/objective-c/tests/Tests.xcodeproj/project.pbxproj

@@ -1282,6 +1282,7 @@
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"DEBUG=1",
 					"$(inherited)",
+					"HOST_PORT=$(HOST_PORT)",
 				);
 				GCC_SYMBOLS_PRIVATE_EXTERN = NO;
 				GCC_TREAT_WARNINGS_AS_ERRORS = YES;

src/objective-c/tests/run_tests.sh

@@ -59,6 +59,9 @@ xcodebuild \
     -workspace Tests.xcworkspace \
     -scheme AllTests \
     -destination name="iPhone 6" \
+    HOST_PORT_LOCALSSL=localhost:5051 \
+    HOST_PORT_LOCAL=localhost:5050 \
+    HOST_PORT_REMOTE=grpc-test.sandbox.googleapis.com \
     test | xcpretty
 
 echo "TIME:  $(date)"
@@ -84,4 +87,5 @@ xcodebuild \
     -workspace Tests.xcworkspace \
     -scheme InteropTestsRemoteWithCronet \
     -destination name="iPhone 6" \
+    HOST_PORT_REMOTE=grpc-test.sandbox.googleapis.com \
     test | xcpretty