DiscoveryManager: pause and resume discovery providers on app state c…

…hange

ConnectSDKTests/Discovery/DiscoveryManagerTests.m

@@ -0,0 +1,129 @@
+//
+//  DiscoveryManagerTests.m
+//  ConnectSDK
+//
+//  Created by Eugene Nikolskyi on 2015-06-19.
+//  Copyright (c) 2015 LG Electronics. 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 "DiscoveryManager_Private.h"
+
+#import "AppStateChangeNotifier.h"
+#import "DiscoveryProvider.h"
+
+#import "OCMArg+ArgumentCaptor.h"
+
+@interface MockDeviceService : DeviceService @end
+@implementation MockDeviceService
+
++ (NSDictionary *)discoveryParameters {
+    return @{@"serviceId": @"mockService"};
+}
+
+@end
+
+
+
+@interface DiscoveryManagerTests : XCTestCase
+
+@property (nonatomic, strong) DiscoveryManager *discoveryManager;
+@property (nonatomic, strong) id /*AppStateChangeNotifier **/ stateNotifierMock;
+@property (nonatomic, strong) id /*DiscoveryProvider **/ discoveryProviderMock;
+
+@end
+
+@implementation DiscoveryManagerTests
+
+#pragma mark - Setup
+
+- (void)setUp {
+    [super setUp];
+
+    self.stateNotifierMock = OCMClassMock([AppStateChangeNotifier class]);
+    self.discoveryProviderMock = OCMClassMock([DiscoveryProvider class]);
+    self.discoveryManager = [self createDiscoveryManager];
+}
+
+- (DiscoveryManager *)createDiscoveryManager {
+    DiscoveryManager *discoveryManager = [[DiscoveryManager alloc]
+                                          initWithAppStateChangeNotifier:self.stateNotifierMock];
+    [discoveryManager registerDeviceService:[MockDeviceService class]
+               withDiscoveryProviderFactory:^{
+                   return self.discoveryProviderMock;
+               }];
+
+    return discoveryManager;
+}
+
+- (void)tearDown {
+    [self.discoveryManager stopDiscovery];
+    self.discoveryManager = nil;
+    self.stateNotifierMock = nil;
+
+    [super tearDown];
+}
+
+#pragma mark - UIApplication State Change Tests
+
+- (void)testDefaultStateNotifierShouldBeCreated {
+    DiscoveryManager *discoveryManager = [DiscoveryManager new];
+    XCTAssertNotNil(discoveryManager.appStateChangeNotifier,
+                    @"a real AppStateChangeNotifier should be created");
+}
+
+- (void)testStartDiscoveryShouldStartListeningStateNotifier {
+    OCMExpect([self.stateNotifierMock startListening]);
+    [self.discoveryManager startDiscovery];
+    OCMVerifyAll(self.stateNotifierMock);
+}
+
+- (void)testStopDiscoveryShouldStopListeningStateNotifier {
+    OCMExpect([self.stateNotifierMock stopListening]);
+    [self.discoveryManager startDiscovery];
+    [self.discoveryManager stopDiscovery];
+    OCMVerifyAll(self.stateNotifierMock);
+}
+
+- (void)testBackgroundingShouldPauseDiscoveryProviders {
+    AppStateChangeBlock backgroundStateBlock;
+    OCMExpect([self.stateNotifierMock setDidBackgroundBlock:
+               [OCMArg captureBlockTo:&backgroundStateBlock]]);
+
+    DiscoveryManager *discoveryManager = [self createDiscoveryManager];
+    [discoveryManager startDiscovery];
+
+    OCMExpect([self.discoveryProviderMock pauseDiscovery]);
+    backgroundStateBlock();
+    OCMVerifyAll(self.discoveryProviderMock);
+}
+
+- (void)testForegroundingShouldResumeDiscoveryProviders {
+    AppStateChangeBlock backgroundStateBlock;
+    AppStateChangeBlock foregroundStateBlock;
+    OCMExpect([self.stateNotifierMock setDidBackgroundBlock:
+               [OCMArg captureBlockTo:&backgroundStateBlock]]);
+    OCMExpect([self.stateNotifierMock setDidForegroundBlock:
+               [OCMArg captureBlockTo:&foregroundStateBlock]]);
+
+    DiscoveryManager *discoveryManager = [self createDiscoveryManager];
+    [discoveryManager startDiscovery];
+
+    backgroundStateBlock();
+    OCMExpect([self.discoveryProviderMock resumeDiscovery]);
+    foregroundStateBlock();
+    OCMVerifyAll(self.discoveryProviderMock);
+}
+
+@end

Discovery/DiscoveryManager.m

@@ -35,6 +35,8 @@
 #import "ServiceConfigDelegate.h"
 #import "CapabilityFilter.h"
 
+#import "AppStateChangeNotifier.h"
+
 #import <SystemConfiguration/CaptiveNetwork.h>
 
 @interface DiscoveryManager() <DiscoveryProviderDelegate, ServiceConfigDelegate>
@@ -96,7 +98,13 @@ - (void) setDeviceStore:(id <ConnectableDeviceStore>)deviceStore
     _useDeviceStore = (_deviceStore != nil);
 }
 
-- (instancetype) init
+- (instancetype)init {
+    return [self initWithAppStateChangeNotifier:nil];
+}
+
+#pragma mark - Private Init
+
+- (instancetype) initWithAppStateChangeNotifier:(nullable AppStateChangeNotifier *)stateNotifier
 {
     self = [super init];
 
@@ -112,6 +120,17 @@ - (instancetype) init
         _allDevices = [[NSMutableDictionary alloc] init];
         _compatibleDevices = [[NSMutableDictionary alloc] init];
 
+        _appStateChangeNotifier = stateNotifier ?: [AppStateChangeNotifier new];
+        __weak typeof(self) wself = self;
+        _appStateChangeNotifier.didBackgroundBlock = ^{
+            typeof(self) sself = wself;
+            [sself pauseDiscovery];
+        };
+        _appStateChangeNotifier.didForegroundBlock = ^{
+            typeof(self) sself = wself;
+            [sself resumeDiscovery];
+        };
+
         [self startSSIDTimer];
     }
 
@@ -445,8 +464,7 @@ - (void) startDiscovery
         [service startDiscovery];
     }];
 
-    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(hAppDidEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
-    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(hAppDidBecomeActive:) name:UIApplicationDidBecomeActiveNotification object:nil];
+    [self.appStateChangeNotifier startListening];
 }
 
 - (void) stopDiscovery
@@ -462,8 +480,35 @@ - (void) stopDiscovery
 
     if (!_shouldResumeSearch)
     {
-        [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
-        [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidBecomeActiveNotification object:nil];
+        [self.appStateChangeNotifier stopListening];
+    }
+}
+
+/// Pauses all discovery providers and the SSID change timer.
+- (void)pauseDiscovery {
+    // moved from -hAppDidEnterBackground:
+    [self stopSSIDTimer];
+
+    if (_searching)
+    {
+        _searching = NO;
+        _shouldResumeSearch = YES;
+
+        [self.discoveryProviders makeObjectsPerformSelector:@selector(pauseDiscovery)];
+    }
+}
+
+/// Resumes all discovery providers and the SSID change timer.
+- (void)resumeDiscovery {
+    // moved from -hAppDidBecomeActive:
+    [self startSSIDTimer];
+
+    if (_shouldResumeSearch)
+    {
+        _searching = YES;
+        _shouldResumeSearch = NO;
+
+        [self.discoveryProviders makeObjectsPerformSelector:@selector(resumeDiscovery)];
     }
 }
 
@@ -654,36 +699,6 @@ - (ConnectableDevice *) lookupMatchingDeviceForDeviceStore:(ServiceConfig *)serv
     return foundDevice;
 }
 
-#pragma mark - Handle background state
-
-- (void) hAppDidEnterBackground:(NSNotification *)notification
-{
-    [self stopSSIDTimer];
-
-    if (_searching)
-    {
-        _shouldResumeSearch = YES;
-        [self stopDiscovery];
-    }
-}
-
-- (void) hAppDidBecomeActive:(NSNotification *)notification
-{
-    [self startSSIDTimer];
-
-    if (_shouldResumeSearch)
-    {
-        _shouldResumeSearch = NO;
-        [self startDiscovery];
-    }
-}
-
-- (void) dealloc
-{
-    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidBecomeActiveNotification object:nil];
-    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
-}
-
 #pragma mark - Device Picker creation
 
 - (DevicePicker *) devicePicker

Discovery/DiscoveryManager_Private.h

@@ -20,10 +20,20 @@
 
 #import "DiscoveryManager.h"
 
+@class AppStateChangeNotifier;
 @class DiscoveryProvider;
 
+NS_ASSUME_NONNULL_BEGIN
 @interface DiscoveryManager ()
 
+/// An @c AppStateChangeNotifier that allows to track app state changes.
+@property (nonatomic, readonly) AppStateChangeNotifier *appStateChangeNotifier;
+
+
+/// Initializes the instance with the given @c AppStateChangeNotifier. Using
+/// @c nil parameter will create real object.
+- (instancetype)initWithAppStateChangeNotifier:(nullable AppStateChangeNotifier *)stateNotifier;
+
 /**
  * Registers a service with the given @c deviceClass and a @c DiscoveryProvider
  * created by the @c providerFactory.
@@ -32,3 +42,4 @@
  withDiscoveryProviderFactory:(DiscoveryProvider *(^)(void))providerFactory;
 
 @end
+NS_ASSUME_NONNULL_END

Discovery/DiscoveryProvider.h

@@ -70,4 +70,16 @@
  */
 - (void) stopDiscovery;
 
+/**
+ * Pauses the discovery while the app is in background. Calls @c -stopDiscovery
+ * by default.
+ */
+- (void)pauseDiscovery;
+
+/**
+ * Resumes the discovery when the app has foregrounded. Calls @c -startDiscovery
+ * be default.
+ */
+- (void)resumeDiscovery;
+
 @end

Discovery/DiscoveryProvider.m

@@ -29,4 +29,12 @@ - (BOOL)isEmpty { return YES; }
 - (void)startDiscovery { }
 - (void)stopDiscovery { }
 
+- (void)pauseDiscovery {
+    [self stopDiscovery];
+}
+
+- (void)resumeDiscovery {
+    [self startDiscovery];
+}
+
 @end