Add example plugin

Summary: Added example plugin for iOS, similar to android

Reviewed By: jknoxville

Differential Revision: D10492429

fbshipit-source-id: d639edc7a47ab240bb172516c2f38b8e2a9f285c

iOS/Plugins/FlipperKitExamplePlugin/FlipperKitExamplePlugin/FlipperKitExamplePlugin.h

@@ -0,0 +1,18 @@
+/*
+ *  Copyright (c) 2018-present, Facebook, Inc.
+ *
+ *  This source code is licensed under the MIT license found in the LICENSE
+ *  file in the root directory of this source tree.
+ *
+ */
+#import <Foundation/Foundation.h>
+#import <FlipperKit/FlipperPlugin.h>
+
+@interface FlipperKitExamplePlugin : NSObject<FlipperPlugin>
+
+- (instancetype)init NS_UNAVAILABLE;
+- (void)sendMessage:(NSString *)msg;
+- (void)triggerNotification;
++ (instancetype) sharedInstance;
+
+@end

iOS/Plugins/FlipperKitExamplePlugin/FlipperKitExamplePlugin/FlipperKitExamplePlugin.mm

@@ -0,0 +1,74 @@
+/*
+ *  Copyright (c) 2018-present, Facebook, Inc.
+ *
+ *  This source code is licensed under the MIT license found in the LICENSE
+ *  file in the root directory of this source tree.
+ *
+ */
+
+#if FB_SONARKIT_ENABLED
+#import "FlipperKitExamplePlugin.h"
+#import <FlipperKit/FlipperClient.h>
+#import <FlipperKit/FlipperConnection.h>
+#import <FlipperKit/FlipperResponder.h>
+
+@interface FlipperKitExamplePlugin()
+@property (strong, nonatomic) NSMutableArray<NSString *> *messagesToDisplay;
+@property (strong, nonatomic) id<FlipperConnection> connection;
+@property (nonatomic) NSInteger triggerCount;
+
+@end
+
+@implementation FlipperKitExamplePlugin
+
+- (instancetype)init {
+    if (self = [super init]) {
+        _messagesToDisplay = @[].mutableCopy;
+        _triggerCount = 0;
+    }
+    return self;
+}
+
++ (instancetype)sharedInstance {
+    static FlipperKitExamplePlugin *sInstance = nil;
+    
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        sInstance = [FlipperKitExamplePlugin new];
+    });
+    
+    return sInstance;
+}
+
+- (void)didConnect:(id<FlipperConnection>)connection {
+    __weak FlipperKitExamplePlugin *weakSelf = self;
+    self.connection = connection;
+    [connection receive:@"displayMessage" withBlock:^(NSDictionary *params, id<FlipperResponder> responder) {
+        [weakSelf.messagesToDisplay addObject:params[@"message"]];
+    }];
+}
+
+- (void)didDisconnect {
+    self.connection = nil;
+}
+
+- (NSString *)identifier {
+    return @"Example";
+}
+
+- (BOOL)runInBackground {
+    return YES;
+}
+
+- (void)sendMessage:(NSString *)msg {
+    [self.connection send:@"displayMessage" withParams:@{@"msg": msg}];
+}
+
+- (void)triggerNotification {
+    [self.connection send:@"triggerNotification" withParams:@{@"id": @(self.triggerCount)}];
+    self.triggerCount++;
+}
+
+@end
+
+#endif