蓝牙术语

BLE ——buletouch low energy，蓝牙低耗电

**peripheral,central **——发起连接的设备是central中心，被连接的设备为perilheral外设

service and characteristic——设备必有的服务和特征，类似于服务端的api，用来操作设备

Description+characteristic——Description用户描述characteristic特征属性

蓝牙状态—— 1. 待机状态（standby）：设备没有传输和发送数据，并且没有连接到任何设 2. 广播状态（Advertiser）：周期性广播状态 3. 扫描状态（Scanner）：主动寻找正在广播的设备 4. 发起链接状态（Initiator）：主动向扫描设备发起连接 5. 主设备（Master）：作为主设备连接到其他设备 6. 从设备（Slave）：作为从设备连接到其他设备

GameKit.framework

只能用于iOS设备之间的连接，多用于游戏（比如五子棋对战），从iOS7开始过期。使用GameKit框架，可以在游戏中增加对等连接，又称对端连接或点对点连接，Peer To Peer。使用GameKit框架中的对等网络连接API，可以在游戏玩家之间建立一个对等网络，并在游戏/应用实例之间交换数据。GameKit框架可以使用蓝牙在玩家之间创建网络，玩家甚至不需要连接到互联网，就可以彼此对战。但是前提必须是都为iOS设备和同一个应用。

// 搜索周边蓝牙设备
GKPeerPickerController *ppc = [[GKPeerPickerController alloc] init];
ppc.delegate = self;
[ppc show];

// 蓝牙连接成功回调
- (void)peerPickerController:(GKPeerPickerController *)picker didConnectPeer:(NSString *)peerID toSession:(GKSession *)session {
    [picker dismiss];
    [session setDataReceiveHandler:self  withContext:nil];
}

// 接收蓝牙数据回调
- (void) receiveData:(NSData *)data fromPeer:(NSString *)peer inSession: (GKSession *)session context:(void *)context {

}

// 利用GKSession发送数据
- (BOOL)sendData:(NSData *) data toPeers:(NSArray *)peers withDataMode:(GKSendDataMode)mode error:(NSError **)error;
- (BOOL)sendDataToAllPeers:(NSData *) data withDataMode:(GKSendDataMode)mode error:(NSError **)error;

MultipeerConnectivity.framework

• 只能用于iOS设备之间的连接，从iOS7开始引入

ExternalAccessory.framework

• 可用于第三方蓝牙设备交互，但是蓝牙设备必须经过苹果MFi认证（国内较少）

CoreBluetooth.framework

CoreBluetooth可与支持蓝牙4.0协议的第三方蓝牙设备交互，蓝牙4.0以低功耗著称，一般也叫BLE（Bluetooth Low Energy）。目前市场上的运动手坏、嵌入式设备（金融刷卡器、心电测量器）、智能家居都是使用此框架。

• 主动连接外设代码7步

1、建立中心设备

CBCentralManager *manager = [[CBCentralManager alloc]initWithDelegate:self queue:dispatch_get_main_queue()];

2、扫描外设（Discover Peripheral）

-(void)centralManagerDidUpdateState:(CBCentralManager *)central{
    switch (central.state) {
        case CBCentralManagerStateUnknown:
            NSLog(@">>>CBCentralManagerStateUnknown");
            break;
        case CBCentralManagerStateResetting:
            NSLog(@">>>CBCentralManagerStateResetting");
            break;
        case CBCentralManagerStateUnsupported:
            NSLog(@">>>CBCentralManagerStateUnsupported");
            break;
        case CBCentralManagerStateUnauthorized:
            NSLog(@">>>CBCentralManagerStateUnauthorized");
            break;
        case CBCentralManagerStatePoweredOff:
            NSLog(@">>>CBCentralManagerStatePoweredOff");
            break;
        case CBCentralManagerStatePoweredOn:
            NSLog(@">>>CBCentralManagerStatePoweredOn");
            [manager scanForPeripheralsWithServices:nil options:nil];
            break;
        default:
            break;
    }
 }

3、连接外设(Connect Peripheral)

//  扫描到外设后回调
-(void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI{
    NSLog(@"当扫描到设备:%@",peripheral.name)；
        /*
         一个主设备最多能连7个外设，每个外设最多只能给一个主设备连接,连接成功，失败，断开会进入各自的委托
         - (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral;//连接外设成功的委托
         - (void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//外设连接失败的委托
         - (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//断开外设的委托
         */
        
   //连接设备
   [manager connectPeripheral:peripheral options:nil];
}

//  连接Peripherals成功
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
{
    NSLog(@">>>连接到名称为（%@）的设备-成功",peripheral.name);
    [peripheral setDelegate:self];
    //扫描外设Services，成功后会进入方法：-(void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error{
    [peripheral discoverServices:nil];
}

//  连接Peripherals失败
-(void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error
{
    NSLog(@">>>连接到名称为（%@）的设备-失败,原因:%@",[peripheral name],[error localizedDescription]);
}

//  Peripherals断开连接
- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error{
    NSLog(@">>>外设连接断开连接 %@: %@\n", [peripheral name], [error localizedDescription]);   
}

4、扫描外设中的服务和特征(Discover Services And Characteristics)

//  扫描外设的Services
-(void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error{
    if (error) {
        NSLog(@">>>Discovered services for %@ with error: %@", peripheral.name, [error localizedDescription]);
        return;
    }
    
    for (CBService *service in peripheral.services) {
        //扫描每个service的Characteristics，扫描到后会进入方法： -(void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error
        [peripheral discoverCharacteristics:nil forService:service];
    }
}

//  获取外设的Characteristics,获取Characteristics的值，获取Characteristics的Descriptor和Descriptor的值
-(void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error{
    if (error)
    {
        NSLog(@"error Discovered characteristics for %@ with error: %@", service.UUID, [error localizedDescription]);
        return;
    }
    
    for (CBCharacteristic *characteristic in service.characteristics)
    {
        NSLog(@"service:%@ 的 Characteristic: %@",service.UUID,characteristic.UUID);
    }
    
    //获取Characteristic的值，读到数据会进入方法：-(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
    for (CBCharacteristic *characteristic in service.characteristics){
        {
            [peripheral readValueForCharacteristic:characteristic];
        }
    }
    
    //搜索Characteristic的Descriptors，读到数据会进入方法：-(void)peripheral:(CBPeripheral *)peripheral didDiscoverDescriptorsForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
    for (CBCharacteristic *characteristic in service.characteristics){
        [peripheral discoverDescriptorsForCharacteristic:characteristic];
    }
}

//  获取的charateristic的值
-(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{
    //!注意，value的类型是NSData，具体开发时，会根据外设协议制定的方式去解析数据，打印出characteristic的UUID和值
    NSLog(@"characteristic uuid:%@  value:%@",characteristic.UUID,characteristic.value);
    
}

//  搜索到Characteristic的Descriptors
-(void)peripheral:(CBPeripheral *)peripheral didDiscoverDescriptorsForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{
    
    //打印出Characteristic和他的Descriptors
    NSLog(@"characteristic uuid:%@",characteristic.UUID);
    for (CBDescriptor *d in characteristic.descriptors) {
        NSLog(@"Descriptor uuid:%@",d.UUID);
    }
    
}
//  获取到Descriptors的值
-(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForDescriptor:(CBDescriptor *)descriptor error:(NSError *)error{
    //打印出DescriptorsUUID 和value
    //这个descriptor都是对于characteristic的描述，一般都是字符串，所以这里我们转换成字符串去解析
    NSLog(@"characteristic uuid:%@  value:%@",[NSString stringWithFormat:@"%@",descriptor.UUID],descriptor.value);
}

5、利用特征与外设做数据交互(Explore And Interact)

//写数据
-(void)writeCharacteristic:(CBPeripheral *)peripheral characteristic:(CBCharacteristic *)characteristic value:(NSData *)value{
    
    //打印出 characteristic 的权限，可以看到有很多种，这是一个NS_OPTIONS，就是可以同时用于好几个值，常见的有read，write，notify，indicate，知知道这几个基本就够用了，前连个是读写权限，后两个都是通知，两种不同的通知方式。
    /*
     typedef NS_OPTIONS(NSUInteger, CBCharacteristicProperties) {
     CBCharacteristicPropertyBroadcast                                              = 0x01,
     CBCharacteristicPropertyRead                                                   = 0x02,
     CBCharacteristicPropertyWriteWithoutResponse                                   = 0x04,
     CBCharacteristicPropertyWrite                                                  = 0x08,
     CBCharacteristicPropertyNotify                                                 = 0x10,
     CBCharacteristicPropertyIndicate                                               = 0x20,
     CBCharacteristicPropertyAuthenticatedSignedWrites                              = 0x40,
     CBCharacteristicPropertyExtendedProperties                                     = 0x80,
     CBCharacteristicPropertyNotifyEncryptionRequired NS_ENUM_AVAILABLE(NA, 6_0)        = 0x100,
     CBCharacteristicPropertyIndicateEncryptionRequired NS_ENUM_AVAILABLE(NA, 6_0)  = 0x200
     };
     
     */
    NSLog(@"%lu", (unsigned long)characteristic.properties);
    
    
    //只有 characteristic.properties 有write的权限才可以写
    if(characteristic.properties & CBCharacteristicPropertyWrite){
        /*
         最好一个type参数可以为CBCharacteristicWriteWithResponse或type:CBCharacteristicWriteWithResponse,区别是是否会有反馈
         */
        [peripheral writeValue:value forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse];
    }else{
        NSLog(@"该字段不可写！");
    }
    
}

6、订阅Characteristic的通知

//设置通知
-(void)notifyCharacteristic:(CBPeripheral *)peripheral
characteristic:(CBCharacteristic *)characteristic{
    //设置通知，数据通知会进入：didUpdateValueForCharacteristic方法
    [peripheral setNotifyValue:YES forCharacteristic:characteristic];
    
}

//取消通知
-(void)cancelNotifyCharacteristic:(CBPeripheral *)peripheral
characteristic:(CBCharacteristic *)characteristic{
    
    [peripheral setNotifyValue:NO forCharacteristic:characteristic];
}

7、断开连接(Disconnect)

-(void)disconnectPeripheral:(CBCentralManager *)centralManager peripheral:(CBPeripheral *)peripheral{
    //停止扫描
    [centralManager stopScan];
    //断开连接
    [centralManager cancelPeripheralConnection:peripheral];
}

• 被动连接外设代码4步

1、启动一个外设管理对象peripheralManager，设置peripheralManager的委托

待续

2、本地Peripheral设置服务,特性,描述,权限等等

待续

3、Peripheral开启广播advertising

待续

4、对central的操作进行响应

//  读characteristics请求

//  写characteristics请求

//  订阅和取消订阅characteristics