Added helloworld sample with Bazel build

examples/objective-c/BUILD

@@ -0,0 +1,57 @@
+# Copyright 2019 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+licenses(["notice"])  # 3-clause BSD
+
+package(default_visibility = ["//visibility:public"])
+
+load("@com_github_grpc_grpc//bazel:objc_grpc_library.bzl", "objc_grpc_library")
+load("@build_bazel_rules_apple//apple:ios.bzl", "ios_application")
+
+objc_grpc_library(
+    name = "HelloWorld_grpc_proto",
+    srcs = ["//examples:protos/helloworld.proto"],
+    deps = ["//examples:helloworld_proto"],
+)
+
+# This one works with import "external/com_github_grpc_grpc/examples/protos/Helloworld.pbrpc.h"
+objc_grpc_library(
+    name = "HelloWorld_grpc_proto_external",
+    srcs = ["//external/com_github_grpc_grpc/examples:protos/helloworld.proto"],
+    deps = ["@com_github_grpc_grpc//examples:helloworld_proto"],
+)
+
+objc_library(
+    name = "HelloWorld-lib",
+    srcs = glob(["helloworld/**/*.m",]),
+    hdrs = glob(["helloworld/**/*.h"]),
+    data = glob([
+        "helloworld/HelloWorld/Base.lproj/**",
+        "helloworld/HelloWorld/Images.xcassets/**",
+    ]),
+    includes = ["helloworld/HelloWorld"],
+    deps = [":HelloWorld_grpc_proto"],
+)
+
+ios_application(
+    name = "HelloWorld",
+    bundle_id = "Google.HelloWorld",
+    families = [
+        "iphone",
+        "ipad",
+    ],
+    minimum_os_version = "8.0",
+    infoplists = ["helloworld/HelloWorld/Info.plist"],
+    deps = [":HelloWorld-lib"],
+)

examples/objective-c/helloworld/main.m

@@ -21,7 +21,11 @@
 
 #import <GRPCClient/GRPCCall+ChannelArg.h>
 #import <GRPCClient/GRPCCall+Tests.h>
+#if COCOAPODS
 #import <HelloWorld/Helloworld.pbrpc.h>
+#else
+#import "examples/protos/Helloworld.pbrpc.h"
+#endif
 
 static NSString * const kHostAddress = @"localhost:50051";