BLE蓝牙开发 (三) 手机作为外设开发

peripheral模式的流程：

1. 设置CBPeripheralManagerDelegate的委托,初始化外围设备
2. 检测外设的蓝牙状态
3. 创建服务(service)和特征(characteristics)
4. 开始广播 （中心设备收到广播后连接外设，并进行一系列的请求）
5. 响应center的操作
    * 读写characteristics
    * 订阅和取消订阅characteristics

实现步骤：

1. 初始化外设

    self.periperalMgr = [[CBPeripheralManager alloc] initWithDelegate:self queue:dispatch_get_main_queue()];

2. 检测外设的蓝牙状态后创建服务(service)和特征(characteristics)

#pragma mark - CBPeripheralManagerDelegate -
- (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral {
    /*
     CBManagerStateUnknown = 0,     // 未知
     CBManagerStateResetting,       // 重置中
     CBManagerStateUnsupported,     // 不支持
     CBManagerStateUnauthorized,    // 未验证
     CBManagerStatePoweredOff,      // 关闭
     CBManagerStatePoweredOn,       // 开启
     */
    if(peripheral.state == CBManagerStatePoweredOn) {
        // 2. 创建服务（Service）和特征（Characteristics）
        [self setup];
        
    }
}

3.创建服务和特征

// 安装特征和服务
- (void)setup {
    
    // 创建服务的UUID
    CBUUID *serviceUUID = [CBUUID UUIDWithString:SERVICE_UUID];
    
    // 创建服务
    CBMutableService *service = [[CBMutableService alloc] initWithType:serviceUUID primary:YES];
    
    // 创建特征的UUID
    CBUUID *characteristicUUID = [CBUUID UUIDWithString:CHARACTERISTIC_UUID];
    
    // 注意: value设置为nil  创建一个可读写，可订阅的characteristic
    CBMutableCharacteristic *characteristic = [[CBMutableCharacteristic alloc] initWithType:characteristicUUID properties:CBCharacteristicPropertyRead | CBCharacteristicPropertyWrite value:nil permissions:CBAttributePermissionsReadable | CBAttributePermissionsWriteable];
    
    // 把特征放进服务中
    service.characteristics = @[characteristic];
    
    // 把服务器添加到外设中
    //添加后就会调用代理的- (void)peripheralManager:(CBPeripheralManager *)peripheral didAddService:(CBService *)service error:(NSError *)error

    [self.periperalMgr addService:service];
}

4.开始广播

- (void)peripheralManager:(CBPeripheralManager *)peripheral didAddService:(CBService *)service error:(NSError *)error
{
    // 开始广播
    [self.periperalMgr startAdvertising:@{
                                          CBAdvertisementDataServiceUUIDsKey:@[[CBUUID UUIDWithString:SERVICE_UUID]]
                                          }];

}

//peripheral开始发送advertising
- (void)peripheralManagerDidStartAdvertising:(CBPeripheralManager *)peripheral error:(NSError *)error
{
    
}

5.响应center操作

//中心设备读characteristics请求
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveReadRequest:(CBATTRequest *)request{

    //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.periperalMgr respondToRequest:request withResult:CBATTErrorSuccess];
    }else{
        [self.periperalMgr respondToRequest:request withResult:CBATTErrorWriteNotPermitted];
    }
}
//中心设备写characteristics请求
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray *)requests{
    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 *myCharacteristic =(CBMutableCharacteristic *)request.characteristic;
        myCharacteristic.value = request.value;
        [self.periperalMgr respondToRequest:request withResult:CBATTErrorSuccess];
    }else{
        [self.periperalMgr respondToRequest:request withResult:CBATTErrorWriteNotPermitted];
    }
}