iOS 蓝牙开发（二）iOS 连接外设的代码实现

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

1. 建立中心角色

2. 扫描外设（discover）

3. 连接外设(connect)

4. 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)

准备环境

 1 Xcode

 2 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）

 3 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
    @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];
    }

8 模拟器蓝牙调试，慎用，最好还是用真机去调试。

由于在iPhone 4s之后的iOS才支持BLE，新一代的这些iOS设备又都不便宜，在做测试的时候，用iOS模拟器进行调试，可以节约一些开发成本。怎么在iOS模拟器上调试BLE，

苹果最初给出的说明是，支持BLE的mac机子上可以用模拟器进行调试，并给出了一份技术文档（传送门），恶心的是，后来苹果抽风，又把这份文档移除，

并且把iOS 7.0的模拟器上对BLE的支持也移除掉了（难道是想让大家多买设备测试？Apple sucks.）后面，网上搜了一下，解决办法如下：

1. 买一个CSR蓝牙4.0 USB适配器（某宝上大概30块钱），在机子上插入该物（你懂的）

2. 在Terminal下敲入sudo nvram bluetoothHostControllerSwitchBehavior="never" ， 重启Mac。

3. 用XCode 4.6调试代码，在iOS 6.1的模拟器上跑程序（用XCode 5.0跑iOS 7.0模拟器会抛异常，原因上面详诉过了，Apple sucks，你懂的）

如何降低模拟器的iOS版本呢？

XCode->Preferences->Downloads里面有很多simulators你可以下载

选择个6.1的下载好了