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iOS蓝牙开发（二）：iOS连接外设的代码实现

上一篇文章介绍了蓝牙的技术知识，这里我们具体说明一下中心模式的应用场景。主设备（手机去扫描连接外设，发现外设服务和属性，操作服务和属性的应用。一般来说，外设（蓝牙设备，比如智能手环之类的东西），会由硬件工程师开发好，并定义好设备提供的服务，每个服务对于的特征，每个特征的属性（只读，只写，通知等等），本文例子的业务场景，就是用一手机app去读写蓝牙设备。

##ios连接外设的代码实现流程

建立中心角色
扫描外设（discover）
连接外设(connect)
扫描外设中的服务和特征(discover)

- 4.1 获取外设的services

- 4.2 获取外设的Characteristics,获取Characteristics的值，获取Characteristics的Descriptor和Descriptor的值

5. 与外设做数据交互(explore and interact)

6. 订阅Characteristic的通知

7.断开连接(disconnect)

8.模拟器蓝牙调试，慎用，最好还是用真机去调试。

##准备环境

Xcode
开发证书和手机（蓝牙程序需要使用使用真机调试，使用模拟器也可以调试，但是方法很蛋疼，我会放在最后说）
蓝牙外设

##实现步骤

###1 导入CoreBluetooth头文件，建立主设备管理类，设置主设备委托

#import [CoreBluetooth/CoreBluetooth.h]（因识别问题，此处将尖括号改为方括号）     @interface ViewController : UIViewController    @interface ViewController (){         //系统蓝牙设备管理对象，可以把他理解为主设备，通过他，可以去扫描和链接外设         CBCentralManager *manager;     }      - (void)viewDidLoad {         [super viewDidLoad];         /*          设置主设备的委托,CBCentralManagerDelegate             必须实现的：             - (void)centralManagerDidUpdateState:(CBCentralManager *)central;//主设备状态改变的委托，在初始化CBCentralManager的适合会打开设备，只有当设备正确打开后才能使用             其他选择实现的委托中比较重要的：             - (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI; //找到外设的委托             - (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         */          //初始化并设置委托和线程队列，最好一个线程的参数可以为nil，默认会就main线程          manager = [[CBCentralManager alloc]initWithDelegate:self queue:dispatch_get_main_queue()];

###2 扫描外设（discover），扫描外设的方法我们放在centralManager成功打开的委托中，因为只有设备成功打开，才能开始扫描，否则会报错。

-(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");                     //开始扫描周围的外设                     /*                      第一个参数nil就是扫描周围所有的外设，扫描到外设后会进入                           - (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI;                      */                     [manager scanForPeripheralsWithServices:nil options:nil];                     break;                 default:                     break;             }          }         //扫描到设备会进入方法         -(void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI{              NSLog(@"当扫描到设备:%@",peripheral.name);             //接下来可以连接设备         }

###3 连接外设(connect)

//扫描到设备会进入方法         -(void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI{             //接下连接我们的测试设备，如果你没有设备，可以下载一个app叫lightbule的app去模拟一个设备             //这里自己去设置下连接规则，我设置的是P开头的设备                    if ([peripheral.name hasPrefix:@"P"]){                    /*                        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];                }         }          //连接到Peripherals-成功         - (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral         {             NSLog(@">>>连接到名称为（%@）的设备-成功",peripheral.name);         }          //连接到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)

设备连接成功后，就可以扫描设备的服务了，同样是通过委托形式，扫描到结果后会进入委托方法。但是这个委托已经不再是主设备的委托（CBCentralManagerDelegate），而是外设的委托（CBPeripheralDelegate）,这个委托包含了主设备与外设交互的许多回叫方法，包括获取services，获取characteristics，获取characteristics的值，获取characteristics的Descriptor，和Descriptor的值，写数据，读rssi，用通知的方式订阅数据等等。

4.1获取外设的services

//连接到Peripherals-成功         - (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral         {             NSLog(@">>>连接到名称为（%@）的设备-成功",peripheral.name);             //设置的peripheral委托CBPeripheralDelegate             //@interface ViewController : UIViewController            [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];          }         //扫描到Services         -(void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error{             //  NSLog(@">>>扫描到服务：%@",peripheral.services);             if (error)             {                 NSLog(@">>>Discovered services for %@ with error: %@", peripheral.name, [error localizedDescription]);                 return;             }              for (CBService *service in peripheral.services) {                              NSLog(@"%@",service.UUID);                              //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];                          }          }

4.2获取外设的Characteristics,获取Characteristics的值，获取Characteristics的Descriptor和Descriptor的值

//扫描到Characteristics      -(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{         //打印出characteristic的UUID和值         //!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         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 把数据写到Characteristic中

//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)

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