[Swift] Moves grpc example to grpc/examples (#6479)

Updates generated Code

Removes grpc generation code from tests dir

Small fix to generate.sh

grpc/examples/swift/Greeter/Sources/client/main.swift

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2021 Google Inc. All rights reserved.
+ *
+ * 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.
+ */
+
+import FlatBuffers
+import GRPC
+import Logging
+import Model
+import NIO
+
+// Quieten the logs.
+LoggingSystem.bootstrap {
+  var handler = StreamLogHandler.standardOutput(label: $0)
+  handler.logLevel = .critical
+  return handler
+}
+
+func greet(name: String, client greeter: models_GreeterServiceClient) {
+  // Form the request with the name, if one was provided.
+  var builder = FlatBufferBuilder()
+  let nameOff = builder.create(string: name)
+  let root = models_HelloRequest.createHelloRequest(
+    &builder,
+    nameOffset: nameOff)
+  builder.finish(offset: root)
+
+  // Make the RPC call to the server.
+  let sayHello = greeter.SayHello(Message<models_HelloRequest>(builder: &builder))
+
+  // wait() on the response to stop the program from exiting before the response is received.
+  do {
+    let response = try sayHello.response.wait()
+    print("Greeter SayHello received: \(response.object.message ?? "Unknown")")
+  } catch {
+    print("Greeter failed: \(error)")
+  }
+
+  let surname = builder.create(string: name)
+  let manyRoot = models_HelloRequest.createHelloRequest(
+    &builder,
+    nameOffset: surname)
+  builder.finish(offset: manyRoot)
+
+  let call = greeter.SayManyHellos(Message(builder: &builder)) { message in
+    print("Greeter SayManyHellos received: \(message.object.message  ?? "Unknown")")
+  }
+
+  let status = try! call.status.recover { _ in .processingError }.wait()
+  if status.code != .ok {
+    print("RPC failed: \(status)")
+  }
+}
+
+func main(args: [String]) {
+  // arg0 (dropped) is the program name. We expect arg1 to be the port, and arg2 (optional) to be
+  // the name sent in the request.
+  let arg1 = args.dropFirst(1).first
+  let arg2 = args.dropFirst(2).first
+
+  switch (arg1.flatMap(Int.init), arg2) {
+  case (.none, _):
+    print("Usage: PORT [NAME]")
+    exit(1)
+
+  case let (.some(port), name):
+    // Setup an `EventLoopGroup` for the connection to run on.
+    //
+    // See: https://github.com/apple/swift-nio#eventloops-and-eventloopgroups
+    let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+
+    // Make sure the group is shutdown when we're done with it.
+    defer {
+      try! group.syncShutdownGracefully()
+    }
+
+    // Configure the channel, we're not using TLS so the connection is `insecure`.
+    let channel = ClientConnection.insecure(group: group)
+      .connect(host: "localhost", port: port)
+
+    // Close the connection when we're done with it.
+    defer {
+      try! channel.close().wait()
+    }
+
+    // Provide the connection to the generated client.
+    let greeter = models_GreeterServiceClient(channel: channel)
+
+    // Do the greeting.
+    greet(name: name ?? "FlatBuffers!", client: greeter)
+  }
+}
+
+main(args: CommandLine.arguments)