Add FLIPPER_PORTS env var to iOS SDK

Summary:
Part 2 of changing flipper to use customizable ports: iOS SDK.
Still to go: JS app.

env var should be of the format:

`FLIPPER_PORTS=1111,2222` for insecure port: 1111 and secure port: 2222.

Reviewed By: danielbuechele

Differential Revision: D13800988

fbshipit-source-id: 3560ba850389964f4b784551b803c45c6524e6f0

iOS/FlipperKit/FlipperClient.mm

@@ -16,6 +16,7 @@
 #include "SKStateUpdateCPPWrapper.h"
 #import "FlipperDiagnosticsViewController.h"
 #import "FlipperClient+Testing.h"
+#import "SKEnvironmentVariables.h"
 
 #if !TARGET_OS_SIMULATOR
 #import <FKPortForwarding/FKPortForwardingServer.h>
@@ -82,7 +83,9 @@ using WrapperPlugin = facebook::flipper::FlipperCppWrapperPlugin;
           [privateAppDirectory UTF8String],
         },
         sonarThread.getEventBase(),
-        connectionThread.getEventBase()
+        connectionThread.getEventBase(),
+        [SKEnvironmentVariables getInsecurePort],
+        [SKEnvironmentVariables getSecurePort]
       });
       _cppClient = facebook::flipper::FlipperClient::instance();
     } catch (const std::system_error &e) {

iOS/FlipperKit/SKEnvironmentVariables.h

@@ -0,0 +1,17 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the LICENSE
+ * file in the root directory of this source tree.
+ */
+#ifdef FB_SONARKIT_ENABLED
+
+/*
+ * This class exists to retreive configuration values stored in environment variables.
+ */
+@interface SKEnvironmentVariables : NSObject
+    + (int)getInsecurePort;
+    + (int)getSecurePort;
+@end
+
+#endif

iOS/FlipperKit/SKEnvironmentVariables.m

@@ -0,0 +1,30 @@
+#ifdef FB_SONARKIT_ENABLED
+
+#import "SKEnvironmentVariables.h"
+
+static int const DEFAULT_INSECURE_PORT = 8089;
+static int const DEFAULT_SECURE_PORT = 8088;
+
+@implementation SKEnvironmentVariables
+
++ (int)getInsecurePort {
+    NSString *envVar = [self getFlipperPortsVariable];
+    return [self extractIntFromPropValue:envVar atIndex:0 withDefault:DEFAULT_INSECURE_PORT];
+}
++ (int)getSecurePort {
+    NSString *envVar = [self getFlipperPortsVariable];
+   return [self extractIntFromPropValue:envVar atIndex:1 withDefault:DEFAULT_SECURE_PORT];
+}
++ (int)extractIntFromPropValue:(NSString *)propValue atIndex:(int)index withDefault:(int)fallback {
+    NSArray<NSString *> *components = [propValue componentsSeparatedByString:@","];
+    NSString *component = [components objectAtIndex:index];
+    int envInt = [component intValue];
+    return envInt > 0 ? envInt : fallback;
+}
++ (NSString *)getFlipperPortsVariable {
+    NSString *value = NSProcessInfo.processInfo.environment[@"FLIPPER_PORTS"];
+    return value;
+}
+@end
+
+#endif