[platform_channels] adds EventChannel implementation for iOS (#595)

platform_channels/ios/.gitignore

@@ -21,6 +21,7 @@ Flutter/Generated.xcconfig
 Flutter/app.flx
 Flutter/app.zip
 Flutter/flutter_assets/
+Flutter/.last_build_id
 Flutter/flutter_export_environment.sh
 ServiceDefinitions.json
 Runner/GeneratedPluginRegistrant.*

platform_channels/ios/Flutter/.last_build_id

@@ -1 +0,0 @@
-dad366ac47fa5a1d30c8533697937d44

platform_channels/ios/Runner.xcodeproj/project.pbxproj

@@ -3,11 +3,12 @@
 	archiveVersion = 1;
 	classes = {
 	};
-	objectVersion = 46;
+	objectVersion = 50;
 	objects = {
 
 /* Begin PBXBuildFile section */
 		1498D2341E8E89220040F4C2 /* GeneratedPluginRegistrant.m in Sources */ = {isa = PBXBuildFile; fileRef = 1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */; };
+		1C7DB94C2561121200101D94 /* AccelerometerStreamHandler.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1C7DB94B2561121200101D94 /* AccelerometerStreamHandler.swift */; };
 		3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };
 		74858FAF1ED2DC5600515810 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 74858FAE1ED2DC5600515810 /* AppDelegate.swift */; };
 		97C146FC1CF9000F007C117D /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FA1CF9000F007C117D /* Main.storyboard */; };
@@ -31,6 +32,7 @@
 /* Begin PBXFileReference section */
 		1498D2321E8E86230040F4C2 /* GeneratedPluginRegistrant.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GeneratedPluginRegistrant.h; sourceTree = "<group>"; };
 		1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GeneratedPluginRegistrant.m; sourceTree = "<group>"; };
+		1C7DB94B2561121200101D94 /* AccelerometerStreamHandler.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AccelerometerStreamHandler.swift; sourceTree = "<group>"; };
 		3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = AppFrameworkInfo.plist; path = Flutter/AppFrameworkInfo.plist; sourceTree = "<group>"; };
 		74858FAD1ED2DC5600515810 /* Runner-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "Runner-Bridging-Header.h"; sourceTree = "<group>"; };
 		74858FAE1ED2DC5600515810 /* AppDelegate.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
@@ -95,6 +97,7 @@
 				1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */,
 				74858FAE1ED2DC5600515810 /* AppDelegate.swift */,
 				74858FAD1ED2DC5600515810 /* Runner-Bridging-Header.h */,
+				1C7DB94B2561121200101D94 /* AccelerometerStreamHandler.swift */,
 			);
 			path = Runner;
 			sourceTree = "<group>";
@@ -214,6 +217,7 @@
 			files = (
 				74858FAF1ED2DC5600515810 /* AppDelegate.swift in Sources */,
 				1498D2341E8E89220040F4C2 /* GeneratedPluginRegistrant.m in Sources */,
+				1C7DB94C2561121200101D94 /* AccelerometerStreamHandler.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -302,7 +306,10 @@
 					"$(PROJECT_DIR)/Flutter",
 				);
 				INFOPLIST_FILE = Runner/Info.plist;
-				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+				);
 				LIBRARY_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(PROJECT_DIR)/Flutter",
@@ -415,7 +422,8 @@
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SUPPORTED_PLATFORMS = iphoneos;
-				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
+				SWIFT_COMPILATION_MODE = wholemodule;
+				SWIFT_OPTIMIZATION_LEVEL = "-O";
 				TARGETED_DEVICE_FAMILY = "1,2";
 				VALIDATE_PRODUCT = YES;
 			};
@@ -434,7 +442,10 @@
 					"$(PROJECT_DIR)/Flutter",
 				);
 				INFOPLIST_FILE = Runner/Info.plist;
-				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+				);
 				LIBRARY_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(PROJECT_DIR)/Flutter",
@@ -461,7 +472,10 @@
 					"$(PROJECT_DIR)/Flutter",
 				);
 				INFOPLIST_FILE = Runner/Info.plist;
-				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+				);
 				LIBRARY_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(PROJECT_DIR)/Flutter",

platform_channels/ios/Runner/AccelerometerStreamHandler.swift

@@ -0,0 +1,38 @@
+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import CoreMotion
+
+class AccelerometerStreamHandler: NSObject, FlutterStreamHandler {
+    
+    var motionManger: CMMotionManager;
+    
+    override init() {
+        motionManger = CMMotionManager()
+    }
+    
+    func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink) -> FlutterError? {
+        
+        if !motionManger.isAccelerometerAvailable {
+            events(FlutterError(code: "SENSOR_UNAVAILABLE", message: "Accelerometer is not available", details: nil))
+        }
+        
+        motionManger.accelerometerUpdateInterval = 0.1
+        
+        motionManger.startAccelerometerUpdates(to: OperationQueue.main) {(data, error) in
+            guard let accelerationData = data?.acceleration else {
+                events(FlutterError(code: "DATA_UNAVAILABLE", message: "Cannot get accelerometer data", details: nil ))
+                return
+            }
+            
+            events([accelerationData.x, accelerationData.y, accelerationData.z])
+        }
+        
+        return nil
+    }
+    
+    func onCancel(withArguments arguments: Any?) -> FlutterError? {
+        return nil
+    }
+}

platform_channels/ios/Runner/AppDelegate.swift

@@ -1,3 +1,7 @@
+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 import UIKit
 import Flutter
 
@@ -39,6 +43,8 @@ import Flutter
             }
         }
         
+        FlutterEventChannel(name: "eventChannelDemo", binaryMessenger: flutterViewController.binaryMessenger).setStreamHandler(AccelerometerStreamHandler())
+        
         GeneratedPluginRegistrant.register(with: self)
         return super.application(application, didFinishLaunchingWithOptions: launchOptions)
     }

platform_channels/lib/src/event_channel_demo.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:platform_channels/src/accelerometer_event_channel.dart';
 
 /// Demonstrates how to use [EventChannel] to listen continuous values
@@ -25,7 +26,7 @@ class EventChannelDemo extends StatelessWidget {
           stream: Accelerometer.readings,
           builder: (context, snapshot) {
             if (snapshot.hasError) {
-              return Text(snapshot.error.toString());
+              return Text((snapshot.error as PlatformException).message);
             } else if (snapshot.hasData) {
               return Column(
                 mainAxisAlignment: MainAxisAlignment.center,