一、前言
BLE，全称蓝牙低能耗(Bluetooth Low Energy)技术是低成本、短距离、可互操作的鲁棒性无线技术，工作在免许可的2.4GHz ISM射频频段，隶属于蓝牙4.0规范。它从一开始就设计为超低功耗(ULP)无线技术。它利用许多智能手段最大限度地降低功耗。蓝牙低能耗技术采用可变连接时间间隔，这个间隔根据具体应用可以设置为几毫秒到几秒不等。另外，因为BLE技术采用非常快速的连接方式，因此平时可以处于“非连接”状态（节省能源），此时链路两端相互间只是知晓对方，只有在必要时才开启链路，然后在尽可能短的时间内关闭链路
iOS开发中常用的蓝牙框架也就下面这几个。GameKit.framework，一般用于游戏开发中iOS设备之间的连接；MultipeerConnectivity.framework，iOS7后推出，个人理解可以实现airdrop类似的功能；ExternalAccessory.framework，可用于基于MFI认证的设备连接；CoreBluetooth.framework，低功耗蓝牙，基于蓝牙4.0，开放度高。大部分场景下采用的都是CoreBluetooth.framework，比如现在常见的物联网设备
CoreBluetooth.framework框架结构如下图所示，基于CoreBluetooth.framework做蓝牙开发，我们首先需要了解几个概念
中心设备(central)、外设(peripheral)：这两个概念放在一起说明比较容易理解。比如当你用摩拜App去解锁自行车的时候，你的手机就是中心设备，摩拜车就是外设。如果是从mac利用airdrop传文件到手机，那么电脑就是中心设备，你的手机则又变成了外设。对应结构图中就有中心模式(CBCentralManager)和外设模式(CBPeripheralManager)两种
服务(service)：每个外设一般都会设计若干个服务，每个服务对应一个事件。比如摩拜车，就可能会有一个解锁的服务。每个服务都会有一个唯一的标识(UUID)用于区分。这个标识一般为16bit、32bit或者128bit
特征(characteristic)：每个服务下面可以有若干个特征，设备之间的通讯就是通过这些特征值来实现的。比如在解锁摩拜车的时候，可能会有一个车锁状态的特征，解锁或者锁车之后回去修改这个特征值。同样每个特征也会有一个唯一的标识(UUID)用于区分
特征的属性：对应特征的作用域，某些特征是只读、某些是可读可写、某些是广播等等
基于上面几个概念和结构图，在说明一下使用的流程
1、中心模式：创建对象->搜索外设->连接外设->扫描服务->获取特征->基于特征做数据交互->完成后断开连接
2、外设模式：创建对象->设置服务、特征、属性->发布广播->设置读写等委托方法
下面详细介绍这两种模式的使用方法。其中外设模式在iOS开发中一般使用频率不高，主要为中心模式
二、外设模式
1、引入框架、定义标识
#import <CoreBluetooth/CoreBluetooth.h>
#define notiyCharacteristicUUID @"FFF1"
#define readwriteCharacteristicUUID @"FFF2"
#define readCharacteristicUUID @"FFE1"
#define ServiceUUID1 @"FFF0"
#define ServiceUUID2 @"FFE0"
#define LocalNameKey @"MyBlueDevice"
2、创建外设模式管理，初始化并设置CBPeripheralManagerDelegate代理
@property (nonatomic,strong) CBPeripheralManager *peripheralManager;
self.peripheralManager = [[CBPeripheralManager alloc] initWithDelegate:self queue:nil];
/*
蓝牙设备打开需要一定时间，打开成功后会进入委托方法
- (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral;
模拟器永远也不会得CBPeripheralManagerStatePoweredOn状态，所以做测试的时候请使用真机
*/
3、在回调中初始化服务、特征等
#pragma mark CBPeripheralManagerDelegate
-(void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral
{
switch (peripheral.state) {
case CBManagerStatePoweredOn:
{
NSLog(@"设备已打开....");
[self setupBlueInfo];
break;
}
default:
NSLog(@"异常状态:%ld",(long)peripheral.state);
break;
}
}
-(void)setupBlueInfo
{
CBUUID *CBUUIDCharacteristicUserDescriptionStringUUID = [CBUUID UUIDWithString:CBUUIDCharacteristicUserDescriptionString];
//可以通知的Characteristic
CBMutableCharacteristic *notiyCharacteristic = [[CBMutableCharacteristic alloc]initWithType:[CBUUID UUIDWithString:notiyCharacteristicUUID] properties:CBCharacteristicPropertyNotify value:nil permissions:CBAttributePermissionsReadable];
//可读写的characteristics
self.readwriteCharacteristic = [[CBMutableCharacteristic alloc]initWithType:[CBUUID UUIDWithString:readwriteCharacteristicUUID] properties:CBCharacteristicPropertyWrite | CBCharacteristicPropertyRead value:nil permissions:CBAttributePermissionsReadable | CBAttributePermissionsWriteable];
//设置description
CBMutableDescriptor *readwriteCharacteristicDescription1 = [[CBMutableDescriptor alloc]initWithType: CBUUIDCharacteristicUserDescriptionStringUUID value:@"readwrite"];
[self.readwriteCharacteristic setDescriptors:@[readwriteCharacteristicDescription1]];
//只读的Characteristic
//只有只读属性的特征才能设置初始值，其余设置nil即可，否则在初始化的时候会报错
self.readCharacteristic = [[CBMutableCharacteristic alloc]initWithType:[CBUUID UUIDWithString:readCharacteristicUUID] properties:CBCharacteristicPropertyRead value:[@"readCharacteristic" dataUsingEncoding:NSUTF8StringEncoding] permissions:CBAttributePermissionsReadable];
//service1初始化并加入两个characteristics
CBMutableService *service1 = [[CBMutableService alloc]initWithType:[CBUUID UUIDWithString:ServiceUUID1] primary:YES];
[service1 setCharacteristics:@[notiyCharacteristic,self.readwriteCharacteristic]];
//service2初始化并加入一个characteristics
CBMutableService *service2 = [[CBMutableService alloc]initWithType:[CBUUID UUIDWithString:ServiceUUID2] primary:YES];
[service2 setCharacteristics:@[self.readCharacteristic]];
//添加服务
[self.peripheralManager addService:service1];
[self.peripheralManager addService:service2];
//添加后就会调用代理的- (void)peripheralManager:(CBPeripheralManager *)peripheral didAddService:(CBService *)service error:(NSError *)error
}
-(void)peripheralManager:(CBPeripheralManager *)peripheral didAddService:(CBService *)service error:(NSError *)error
{
if (error == nil) {
self.servicesNum++;
}
//因为我们添加了2个服务，所以想两次都添加完成后才去发送广播
if (self.servicesNum == 2) {
//添加完成之后发送广播
[peripheral startAdvertising:@{CBAdvertisementDataServiceUUIDsKey : @[[CBUUID UUIDWithString:ServiceUUID1],[CBUUID UUIDWithString:ServiceUUID2]],
CBAdvertisementDataLocalNameKey : LocalNameKey}];
//发送广播调用完这个方法后会调用代理的
//(void)peripheralManagerDidStartAdvertising:(CBPeripheralManager *)peripheral error:(NSError *)error
}
}
-(void)peripheralManagerDidStartAdvertising:(CBPeripheralManager *)peripheral error:(NSError *)error
{
NSLog(@"peripheralManagerDidStartAdvertising......");
}
4、处理读写和订阅的委托操作
//订阅characteristics
-(void)peripheralManager:(CBPeripheralManager *)peripheral central:(CBCentral *)central didSubscribeToCharacteristic:(CBCharacteristic *)characteristic{
NSLog(@"订阅了 %@的数据",characteristic.UUID);
[self sendMsg:characteristic];
}
//取消订阅characteristics
-(void)peripheralManager:(CBPeripheralManager *)peripheral central:(CBCentral *)central didUnsubscribeFromCharacteristic:(CBCharacteristic *)characteristic{
NSLog(@"取消订阅 %@的数据",characteristic.UUID);
[self sendMsg:characteristic];
}
//读characteristics请求
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveReadRequest:(CBATTRequest *)request{
NSLog(@"didReceiveReadRequest");
//判断是否有读数据的权限
if (request.characteristic.properties & CBCharacteristicPropertyRead) {
NSData *data = request.characteristic.value;
[request setValue:data];
//对请求作出成功响应
[self.peripheralManager respondToRequest:request withResult:CBATTErrorSuccess];
}else{
[self.peripheralManager respondToRequest:request withResult:CBATTErrorWriteNotPermitted];
}
}
//写characteristics请求
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray *)requests{
NSLog(@"didReceiveWriteRequests");
CBATTRequest *request = requests[0];
//判断是否有写数据的权限
if (request.characteristic.properties & CBCharacteristicPropertyWrite) {
//需要转换成CBMutableCharacteristic对象才能进行写值
CBMutableCharacteristic *c =(CBMutableCharacteristic *)request.characteristic;
c.value = request.value;
[self.peripheralManager respondToRequest:request withResult:CBATTErrorSuccess];
}else{
[self.peripheralManager respondToRequest:request withResult:CBATTErrorWriteNotPermitted];
}
}
//给外设发送消息
- (void)sendMsg:(CBCharacteristic *)characteristic {
[self.peripheralManager updateValue:[@"success" dataUsingEncoding:NSUTF8StringEncoding] forCharacteristic:(CBMutableCharacteristic *)characteristic onSubscribedCentrals:nil];
}
三、中心模式
1、引入框架，创建中心模式管理，初始化并设置CBCentralManagerDelegate代理
#import <CoreBluetooth/CoreBluetooth.h>
@property (nonatomic,strong) CBCentralManager *centerManager;
-(CBCentralManager *)centerManager
{
if (!_centerManager) {
_centerManager = [[CBCentralManager alloc]initWithDelegate:self queue:nil];
//回调-(void)centralManagerDidUpdateState:(CBCentralManager *)central
}
return _centerManager;
}
#pragma mark CBCentralManagerDelegate
-(void)centralManagerDidUpdateState:(CBCentralManager *)central
{
switch (central.state) {
case CBManagerStatePoweredOn:
{
//开始扫描，传nil表示不过滤，扫描所有设备
[self.centerManager scanForPeripheralsWithServices:nil options:nil];
break;
}
default:
NSLog(@"异常状态:%ld",(long)central.state);
break;
}
}
//停止扫描
[self.centralManager stopScan];
2、扫描到设备后连接设备
//扫描到设备后调用
-(void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary<NSString *,id> *)advertisementData RSSI:(NSNumber *)RSSI
{
[self.deviceListArr addObject:peripheral];
[self.tableView reloadData];
}
//点击cell开始连接设备
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
[tableView deselectRowAtIndexPath:indexPath animated:YES];
[self.centerManager stopScan];
CBPeripheral *peripheral = [self.deviceListArr objectAtIndex:indexPath.row];
NSLog(@"+++++++++++++++:%@",peripheral.identifier.UUIDString);
// 连接外设 传入你搜索到的目标外设对象
[self.centerManager connectPeripheral:peripheral options:nil];
}
//连接成功
-(void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
{
NSLog(@"连接成功...");
PeripheralVC *peripheralVC = [[UIStoryboard storyboardWithName:@"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"PeripheralVC"];
peripheralVC.peripheral = peripheral;
[self.navigationController pushViewController:peripheralVC animated:YES];
}
//连接失败
-(void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error
{
NSLog(@"连接失败...");
}
3、扫描服务
设置选择设备的CBPeripheralDelegate并开始扫描服务
self.peripheral.delegate = self;
//扫描所有服务
[self.peripheral discoverServices:nil];
#pragma mark CBPeripheralDelegate
-(void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error
{
if (error) {
NSLog(@"didDiscoverServices:%@",error.localizedDescription);
return;
}
else
{
for (CBService *services in peripheral.services) {
NSLog(@"service UUID:%@",services.UUID.UUIDString);
[self.servicesList addObject:services];
}
}
[self.tableview reloadData];
}
//点击cell之后查找对应服务的特征
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
[tableView deselectRowAtIndexPath:indexPath animated:YES];
CBService *service = [self.servicesList objectAtIndex:indexPath.row];
CharacteristicVC *characteristicVC = [[UIStoryboard storyboardWithName:@"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"CharacteristicVC"];
characteristicVC.peripheral = self.peripheral;
characteristicVC.service = service;
[self.navigationController pushViewController:characteristicVC animated:YES];
}
4、扫描特征
//设置代理
self.peripheral.delegate = self;
#pragma mark CBPeripheralDelegate
-(void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(nonnull CBService *)service error:(nullable NSError *)error
{
if (error) {
NSLog(@"didDiscoverCharacteristicsForService:%@",error.localizedDescription);
return;
}
else
{
for (CBCharacteristic *cha in service.characteristics) {
[self.characteristicList addObject:cha];
switch (cha.properties) {
case CBCharacteristicPropertyRead:
{
NSLog(@"------------------读:%@",cha);
break;
}
case CBCharacteristicPropertyWrite:
{
NSLog(@"------------------写:%@",cha);
break;
}
case CBCharacteristicPropertyNotify:
{
NSLog(@"------------------订阅:%@",cha);
break;
}
default:
NSLog(@"------------------:%@",cha);
break;
}
}
[self.tableView reloadData];
}
}
//点击cell到特征操作页面，开始做数据传输
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
[tableView deselectRowAtIndexPath:indexPath animated:YES];
CBCharacteristic *characteristic = [self.characteristicList objectAtIndex:indexPath.row];
CharacteristicHandleVC *characteristicHandleVC = [[UIStoryboard storyboardWithName:@"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"CharacteristicHandleVC"];
characteristicHandleVC.peripheral = self.peripheral;
characteristicHandleVC.service = self.service;
characteristicHandleVC.characteristic = characteristic;
[self.navigationController pushViewController:characteristicHandleVC animated:YES];
}
5、数据传输
数据传输都是在下面的回调中完成
//设置代理
self.peripheral.delegate = self;
//读数据的回调
-(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
{
self.msgShowLabel.text = [[NSString alloc] initWithData:characteristic.value encoding:NSUTF8StringEncoding];
}
//写数据的回调
-(void)peripheral:(CBPeripheral *)peripheral didWriteValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
{
if (error) {
self.msgShowLabel.text = @"didWriteValueForCharacteristic error";
}
else
{
//读数据
[peripheral readValueForCharacteristic:characteristic];
}
}
- (IBAction)sendMsgBtnClicked:(UIButton *)sender {
//写数据
NSString *msg = [self.msgTextField.text length] > 0 ? self.msgTextField.text : @"无";
[self.peripheral writeValue:[msg dataUsingEncoding:NSUTF8StringEncoding] forCharacteristic:self.characteristic type:CBCharacteristicWriteWithResponse];
}
以上就是基于BLE实现的蓝牙通讯的基本介绍
