聊聊Apple的iBeacon技术

首先,iBeacon 的标志是下面这张图片
聊聊Apple的iBeacon技术_第1张图片
iBeacon

网上查资料说苹果在13年的WWDC上发布iOS7上配备的新功能。
最近,利用iBeacon设备做了下定位的算法研究,故此来总结下,也希望能和大家交流下。

下面进入正题,iBeacon这项技术是苹果建立在低功耗蓝牙的技术上做出来的东西。具体来说是利用BLE中名为"通告帧"的广播帧。通告帧是由配备BLE的设备定期发出,只要是支持BLE的终端,都可以接受到信号。通告帧的有效载荷部分,写入了苹果定义的数据。

一个iBeacon基站的数据大致由四部分信息组成:

  • 1 、UUID(universally unique identifier):一个128位的唯一标识一个或多个Beacon基站为特定类型或特定的组织。
  • 2、 Major:一个16位的无符号整数,可以将具有相同proximity UUID的Beacon基站组织联系起来。(用户可以自定义)
  • 3、 Minor:同上。
  • 4、Measured Power :是iBeacon发送模块与接收器之间距离为1米时的信号强度(RSSI)参照值。

通过蓝牙低功耗技术(BLE)发送特定的识别信息,来确定Beacon基站和设备之间的相对距离。而这个距离并不是精密推算的,而是将其分为三级:

  • 约10厘米(immediate)
  • 1米以内(near)
  • 1米以外(far)
    这是因为,发送和接受设备之间的距离在1米之内时,RSSI值基本是按照理论值减少的,而在1米外,收到发射波的影响,RSSI不会明显的随距离增加减少,而是会上下波动。也就是说,1米外的距离无法非常精密推测,可以用far来概括。

接下来,进入重点:

既然,用一个iBeacon我们可以测出Beacon设备和扫描Beacon设备之间的距离(Apple的API中已给出距离值)。那么,猜想下,有三个Beacon,然后知道他们的坐标信息,那么我们拿着手机去不断的扫描这三个Beacon的RSSI信息就可以利用定位算法来进行定位了。
一篇关于用iBeacon定位的文章

最后,上代码

关于开始定位的部分

    UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeBadge | UIUserNotificationTypeSound | UIUserNotificationTypeAlert categories:nil];
    [[UIApplication sharedApplication] registerUserNotificationSettings:settings];

    self.locationManager            = [[CLLocationManager alloc] init];
    self.locationManager.delegate   = self;
    
    NSArray *myBeacon = @[UUID_BEACON_O, UUID_BEACON_T, UUID_BEACON_H];
    
    for (NSString *uuid in myBeacon) {

        NSString *identifier = @"";
        if ([uuid isEqualToString:UUID_BEACON_O]) {
            
            identifier = @"左后";
        }else if ([uuid isEqualToString:UUID_BEACON_T]) {
        
            identifier = @"右后";
        }else if ([uuid isEqualToString:UUID_BEACON_H]) {
        
            identifier = @"左前";
        }
        
        CLBeaconRegion *beacon = [[CLBeaconRegion alloc] initWithProximityUUID:[[NSUUID alloc] initWithUUIDString:uuid]
                                                                    identifier:identifier];
        beacon.notifyOnExit              = YES;
        beacon.notifyOnEntry             = YES;
        beacon.notifyEntryStateOnDisplay = YES;
        
        [self.locationManager startMonitoringForRegion:beacon];
        [self.locationManager startRangingBeaconsInRegion:beacon];
    }
    
    [self.locationManager requestAlwaysAuthorization];
关于位置的Delegate部分
- (void)locationManager:(CLLocationManager *)manager didEnterRegion:(CLRegion *)region {

    if ([region isKindOfClass:[CLBeaconRegion class]]) {
        
        UILocalNotification *notification = [[UILocalNotification alloc] init];
        notification.alertBody = [NSString stringWithFormat:@"你已进入到 %@ 范围内", region.identifier];
        notification.soundName = @"Default";
        [[UIApplication sharedApplication] presentLocalNotificationNow:notification];
        
        NSLog(@"%@", [NSString stringWithFormat:@"你已进入到 %@ 范围内", region.identifier]);
    }
}

- (void)locationManager:(CLLocationManager *)manager didExitRegion:(CLRegion *)region {

    if ([region isKindOfClass:[CLBeaconRegion class]]) {
        
        UILocalNotification *notification = [[UILocalNotification alloc] init];
        notification.alertBody = [NSString stringWithFormat:@"你已离开 %@ 的范围", region.identifier];
        notification.soundName = @"Default";
        [[UIApplication sharedApplication] presentLocalNotificationNow:notification];
        
        NSLog(@"%@", [NSString stringWithFormat:@"你已离开 %@ 的范围", region.identifier]);
    }
}

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

        for (CLBeacon *beacon in beacons) {
            
    //        NSLog(@"beacon Info : rssi is %ld, major is %@, minor is %@, accuracy is %f, proximity is %ld.", beacon.rssi, beacon.major, beacon.minor, beacon.accuracy, beacon.proximity);
            
            if (self.beaconDataSource.count == 3) {
                
                if ([[beacon.proximityUUID UUIDString] isEqualToString:UUID_BEACON_O]) {
                    [self.beaconDataSource replaceObjectAtIndex:0 withObject:beacon];
                    
                    [self.wait1 addObject:beacon];      //采集数据  左后
                }
                if ([[beacon.proximityUUID UUIDString]isEqualToString:UUID_BEACON_T]) {
                    
                    [self.beaconDataSource replaceObjectAtIndex:1 withObject:beacon];
                    
                    [self.wait2 addObject:beacon];      //采集数据  右后
                }
                if ([[beacon.proximityUUID UUIDString]isEqualToString:UUID_BEACON_H]) {
                    
                    [self.beaconDataSource replaceObjectAtIndex:2 withObject:beacon];
                    
                    [self.wait3 addObject:beacon];      //采集数据  左前
                }
                
                if (!self.testButton.selected) {   //测试按钮没有选中
                   //实时刷新位置信息
                    if (self.wait1.count == 20 && self.wait2.count == 20 && self.wait3.count == 20) {
                        
                        //                    NSArray *result = [DealModel dealWithBaseData:@[@[@"0", @"0"], @[@"220", @"0"], @[@"110", @"110"]] andThreeAuxData:@[self.wait1, self.wait2, self.wait3] andReal:@[self.textX.text, self.textY.text]];
                        DataProcessing *data = [[DataProcessing alloc] init];
                        NSArray *result2 = [data dealWithBaseData:@[@[@"0", @"0"], @[@"220", @"0"], @[@"110", @"110"]] andThreeAuxData:@[self.wait1, self.wait2, self.wait3] andReal:@[@"",@""]];
                        
                        self.result1.text = self.result2.text;
                        self.result2.text = [NSString stringWithFormat:@"X : %@\nY : %@", result2[0], result2[1]];
                        
                        NSLog(@"%@", data);
                        //                self.xyView.center = CGPointMake([result[0] floatValue], [result[1] floatValue]);
                        
                        [self.wait1 removeAllObjects];
                        [self.wait2 removeAllObjects];
                        [self.wait3 removeAllObjects];
                        self.sureButton.selected = NO;
                        self.sureButton.backgroundColor = [UIColor blackColor];
                        
                    }
                    

                }else {
                    //开始测试单个设备误差
                    if (self.wait1.count == 20) {
                        
                        if (![self.textX.text isEqualToString:@""])
                            [DataProcessing testErrorWithUUID:UUID_BEACON_O andRealValue:self.textX.text andTestArray:self.wait1];
                        
                        
                        [self.wait1 removeAllObjects];
                        [self.wait2 removeAllObjects];
                        [self.wait3 removeAllObjects];
                    }else if (self.wait2.count == 20) {
                    
                        if (![self.textX.text isEqualToString:@""])
                            [DataProcessing testErrorWithUUID:UUID_BEACON_T andRealValue:self.textX.text andTestArray:self.wait2];

                        [self.wait1 removeAllObjects];
                        [self.wait2 removeAllObjects];
                        [self.wait3 removeAllObjects];
                    }else if (self.wait3.count == 20) {
                        
                        if (![self.textX.text isEqualToString:@""])
                            [DataProcessing testErrorWithUUID:UUID_BEACON_H andRealValue:self.textX.text andTestArray:self.wait3];

                        [self.wait1 removeAllObjects];
                        [self.wait2 removeAllObjects];
                        [self.wait3 removeAllObjects];
                    }
                }
                
                [self.localView refreshWithArray:self.beaconDataSource];
            }else {
                
                if ([[beacon.proximityUUID UUIDString] isEqualToString:UUID_BEACON_O] || [[beacon.proximityUUID UUIDString]isEqualToString:UUID_BEACON_T] || [[beacon.proximityUUID UUIDString]isEqualToString:UUID_BEACON_H]) {
                    
                    [self.beaconDataSource addObject:beacon];
                }
            }
        }
        
        [self.beaconTableView reloadData];
   
}

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