我需要什么:

启动 iBeacon 委托(delegate)方法的可预测、可靠的方式，例如 didDetermineState、didRangeBeacons、didEnterRegion 或 didExitRegion 当应用程序死机并且设备已插入并位于附近时。

现状

我正在为 parent 开发一款应用，让他们的 child 在重要时刻关掉手机。该应用程序采用 Objective-C 语言，即使在应用程序生命周期结束后，它也需要保持与蓝牙设备的持久连接。

我已经尝试了很长时间才能让它发挥作用，而且我得到了很多 S.O. 的帮助。海报，目前我知道我必须在我的设备中使用 iBeacon 才能从终止启动(这是我使用它的唯一原因，如果有另一种方法从终止启动应用程序，我会很乐意放弃它)。澄清一下，我需要在同一个设备(我已经构建)iBeacon 和稳定的 BT 连接中安装 2 个东西。我需要这个设备连接配对，因为这是从 BT 设备发送/接收命令的唯一方法。我发现在后台触发的 didRange 或 didEnter 委托(delegate)方法充其量是不可靠的。他们并不总是立即开火，他们只开火几次，然后整个事情就结束了(我现在知道这 10 秒的窗口是终止应用程序的预期行为)。我什至有一整天的时间插上/拔下它，不断寻找任何迹象表明该应用程序已经恢复生机，但没有任何反应......

当应用程序打开时，一切正常，但是当应用程序靠近我的信标/蓝牙时，我希望它在应用程序内启动一种临时锁屏。当应用程序在前台时，我已经很好地完成了这一部分。如果一个 child 试图关闭应用程序或它的后台，我想通过让我的 BT 设备在它终止后启动到后台来响应(我知道 UI 不会出现，没关系，我只需要启动一系列功能) .然后它将连接到蓝牙并从设备接收一些命令。听起来很简单吧？事情变得一团糟。

一些上下文:我在 info.plist 中添加了蓝牙和信标的所有后台模式，当应用程序处于前台时一切正常......

如果在范围内检测到 iBeacon，那么我想使用这 10 秒窗口通过 BT 配对连接到我的盒子并通过命令发送。到目前为止，这是不可靠的……当应用程序终止时，iBeacon 测距功能不会触发，它们只会在最奇怪的用例上触发。我似乎无法预测他们何时会开火。

我的代码

ibeaconManager.h

@interface IbeaconManager : NSObject

@property (nonatomic) BOOL waitingForDeviceCommand;
@property (nonatomic, strong) NSTimer *deviceCommandTimer;

+ (IbeaconManager *) sharedInstance;
- (void)startMonitoring;
- (void)stopMonitoring;
- (void)timedLock:(NSTimer *)timer;

@end

ibeaconManager.m

@interface IbeaconManager () <CLLocationManagerDelegate>

@property (nonatomic, strong) BluetoothMgr *btManager;
@property (nonatomic, strong) CLLocationManager *locationManager;
@property (nonatomic, strong) CLBeaconRegion *region;
@property (nonatomic) BOOL connectedToDevice;

@end

NSString *const PROXMITY_UUID = @"00000000-1111-2222-3333-AAAAAAAAAAAA";
NSString *const BEACON_REGION = @"MY_CUSTOM_REGION";

const int REGION_MINOR = 0;
const int REGION_MAJOR = 0;



@implementation IbeaconManager
+ (IbeaconManager *) sharedInstance {
    static IbeaconManager *_sharedInstance = nil;
    static dispatch_once_t oncePredicate;

    dispatch_once(&oncePredicate, ^{
        _sharedInstance = [[IbeaconManager alloc] init];
    });

    return _sharedInstance;

}


- (id)init {
    self = [super init];

    if(self) {
        self.locationManager = [[CLLocationManager alloc] init];
        self.locationManager.delegate = self;
        [self.locationManager requestAlwaysAuthorization];
        self.connectedToDevice = NO;
        self.waitingForDeviceCommand = NO;

        self.region = [[CLBeaconRegion alloc] initWithProximityUUID:[[NSUUID alloc] initWithUUIDString:PROXMITY_UUID]
                                                              major:REGION_MAJOR
                                                              minor:REGION_MINOR
                                                         identifier:BEACON_REGION];

        self.region.notifyEntryStateOnDisplay = YES;
        self.region.notifyOnEntry = YES;
        self.region.notifyOnExit = YES;
    }

    return self;
}


- (void)startMonitoring {
    if(self.region != nil) {
        NSLog(@"**** started monitoring with beacon region **** : %@", self.region);

        [self.locationManager startMonitoringForRegion:self.region];
        [self.locationManager startRangingBeaconsInRegion:self.region];
    }
}


- (void)stopMonitoring {
    NSLog(@"*** stopMonitoring");

    if(self.region != nil) {
        [self.locationManager stopMonitoringForRegion:self.region];
        [self.locationManager stopRangingBeaconsInRegion:self.region];
    }
}


- (void)triggerCustomLocalNotification:(NSString *)alertBody {
    UILocalNotification *localNotification = [[UILocalNotification alloc] init];
    localNotification.alertBody = alertBody;
    [[UIApplication sharedApplication] presentLocalNotificationNow:localNotification];
}




#pragma mark - CLLocationManager delegate methods

- (void)locationManager:(CLLocationManager *)manager
      didDetermineState:(CLRegionState)state
              forRegion:(CLRegion *)region {

    NSLog(@"did determine state STATE: %ld", (long)state);
    NSLog(@"did determine state region: %@", region);

    [self triggerCustomLocalNotification:@"made it into the did determine state method"];

    NSUInteger appState = [[UIApplication sharedApplication] applicationState];
    NSLog(@"application's current state: %ld", (long)appState);

    if(appState == UIApplicationStateBackground || appState == UIApplicationStateInactive) {
        NSString *notificationText = @"Did range beacons... The app is";
        NSString *notificationStateText = (appState == UIApplicationStateInactive) ? @"inactive" : @"backgrounded";
        NSString *notificationString = [NSString stringWithFormat:@"%@ %@", notificationText, notificationStateText];

        NSUserDefaults *userDefaults = [[NSUserDefaults alloc] init];
        bool isAppLockScreenShowing = [userDefaults boolForKey:@"isAppLockScreenShowing"];

        if(!isAppLockScreenShowing && !self.waitingForDeviceCommand) {
            self.waitingForDeviceCommand = YES;

            self.deviceCommandTimer = [NSTimer scheduledTimerWithTimeInterval:2.0
                                                                       target:self
                                                                     selector:@selector(timedLock:)
                                                                     userInfo:notificationString
                                                                      repeats:NO];
        }

    } else if(appState == UIApplicationStateActive) {

        if(region != nil) {
            if(state == CLRegionStateInside) {
                NSLog(@"locationManager didDetermineState INSIDE for %@", region.identifier);
                [self triggerCustomLocalNotification:@"locationManager didDetermineState INSIDE"];

            } else if(state == CLRegionStateOutside) {
                NSLog(@"locationManager didDetermineState OUTSIDE for %@", region.identifier);
                [self triggerCustomLocalNotification:@"locationManager didDetermineState OUTSIDE"];

            } else {
                NSLog(@"locationManager didDetermineState OTHER for %@", region.identifier);
            }
        }

        //Upon re-entry, remove timer
        if(self.deviceCommandTimer != nil) {
            [self.deviceCommandTimer invalidate];
            self.deviceCommandTimer = nil;
        }
    }
}


- (void)locationManager:(CLLocationManager *)manager
        didRangeBeacons:(NSArray *)beacons
               inRegion:(CLBeaconRegion *)region {

    NSLog(@"Did range some beacons");

    NSUInteger state = [[UIApplication sharedApplication] applicationState];
    NSString *notificationStateText = (state == UIApplicationStateInactive) ? @"inactive" : @"backgrounded";
    NSLog(@"application's current state: %ld", (long)state);

    [self triggerCustomLocalNotification:[NSString stringWithFormat:@"ranged beacons, application's current state: %@", notificationStateText]];

    if(state == UIApplicationStateBackground || state == UIApplicationStateInactive) {
        NSString *notificationText = @"Did range beacons... The app is";
        NSString *notificationString = [NSString stringWithFormat:@"%@ %@", notificationText, notificationStateText];

        NSUserDefaults *userDefaults = [[NSUserDefaults alloc] init];
        bool isAppLockScreenShowing = [userDefaults boolForKey:@"isAppLockScreenShowing"];

        if(!isAppLockScreenShowing && !self.waitingForDeviceCommand) {
            self.waitingForDeviceCommand = YES;

            self.deviceCommandTimer = [NSTimer scheduledTimerWithTimeInterval:2.0
                                                                       target:self
                                                                     selector:@selector(timedLock:)
                                                                     userInfo:notificationString
                                                                      repeats:NO];
        }

    } else if(state == UIApplicationStateActive) {
        if(self.deviceCommandTimer != nil) {
            [self.deviceCommandTimer invalidate];
            self.deviceCommandTimer = nil;
        }
    }
}


- (void)timedLock:(NSTimer *)timer {
    self.btManager = [BluetoothMgr sharedInstance];

    [self.btManager sendCodeToBTDevice:@"magiccommand"
                        characteristic:self.btManager.lockCharacteristic];

    [self triggerCustomLocalNotification:[timer userInfo]];

    self.waitingForDeviceCommand = NO;
}


- (void)locationManager:(CLLocationManager *)manager didEnterRegion:(CLRegion *)region {
    NSLog(@"Did Enter Region: %@", region);
    [self triggerCustomLocalNotification:[NSString stringWithFormat:@"Did enter region: %@", region.identifier]];
}


- (void)locationManager:(CLLocationManager *)manager didExitRegion:(CLRegion *)region {
    NSLog(@"Did Exit Region: %@", region);
    [self triggerCustomLocalNotification:[NSString stringWithFormat:@"Did exit region: %@", region.identifier]];

    //Upon exit, remove timer
    if(self.deviceCommandTimer != nil) {
        [self.deviceCommandTimer invalidate];
        self.deviceCommandTimer = nil;
    }
}


- (void)locationManager:(CLLocationManager *)manager monitoringDidFailForRegion:(CLRegion *)region withError:(NSError *)error {
    NSLog(@"monitoringDidFailForRegion EPIC FAIL for region %@ withError %@", region.identifier, error.localizedDescription);
}




@end

最佳答案

我已经为 iOS 构建了一个类似的系统，它使用 iBeacon 传输在后台唤醒，然后连接到蓝牙 LE 以交换数据。 请放心，这一切都是可能的，只是开始工作很棘手，调试起来更棘手。

关于使用蓝牙 LE 连接执行此操作的一些提示:

• 信标测距功能不会在应用程序被终止时触发，除非您还监视信标并获得 didEnter 或 didExit 过渡，这将按照您的描述将应用程序重新启动到后台 10 秒。同样，只有当您从区域内过渡到区域外或反之时，才会发生这种情况。这很难测试，因为当您终止应用程序时，您可能没有意识到 CoreLocation 认为您“在区域内”，但您不会收到用于检测信标的唤醒事件。

• 为了在后台获取蓝牙事件，您需要确保您的 Info.plist 声明如下:

  <key>UIBackgroundModes</key>
  <array>
     <string>bluetooth-central</string>
  </array>
  

  如果不存在，您绝对不会在后台收到对 didDiscoverPeripheral 的回调。

• 您需要在应用启动时开始扫描蓝牙，并在收到回调到 func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any ], rssi RSSI: NSNumber)

• 从上面保存一份 peripheral 实例的副本，因为您只能在后台获得 一个 回调以从每个唯一的蓝牙设备进行发现。如果连接失败，您可以使用相同的 peripheral 对象实例重试。

• 为了调试从终止状态重新启动，我添加了很多 NSLog 语句(我添加了在代码中打开和关闭它们的功能)然后寻找这些在 XCode 的 Windows -> Devices -> My iPhone 面板中，您可以在其中展开屏幕底部的小箭头以显示设备上所有应用程序的日志。如果您的应用从终止状态重新启动，您绝对会在此处看到您的应用的日志。

关于iOS iBeacon/Bluetooth 连接当应用程序死机和消失时，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/45145680/