iOS 蓝牙（中心模式连接外围设备）

最近做一个iOS蓝牙设备的项目，需要用iOS连接外部蓝牙设备，获取设备广播数据，解析展示。就对iOS蓝牙相关内容做了一些学习，在此记录一下。

Core Bluetooth framework中几个主要的类的相关概念如下：

1、中心设备：CBCentral   外围设备管理类： CBPeripheralManager 外围设备的服务 CBMutableService 外围设备的特征 CBMutableCharacteristic 作为外围设备服务特征的唯一标志：CBUUID

2、外围设备：CBPeripheral  中心设备管理类： CBCentralManager  外围设备的服务 ：CBService  外围设备的特征： CBCharacteristic   读写中心设备数据的请求：CBATTRequest

比如 手机连接蓝牙耳机，手机就是中心设备，耳机就是外围设备

iOS蓝牙开发 ios连接外设的实现过程如下：

 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)

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 "ViewController.h"
#import <CoreBluetooth/CoreBluetooth.h>

@interface ViewController ()<CBCentralManagerDelegate,CBPeripheralDelegate>

//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
@property (nonatomic,strong) CBCentralManager *manager;

//用于保存被发现设备
@property (nonatomic,strong) NSMutableArray *peripherals;

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    //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
    self.manager = [[CBCentralManager alloc]initWithDelegate:self queue:dispatch_get_main_queue()];
    self.peripherals = [NSMutableArray new];
}

设置主设备委托，CBCentralManagerDelegate

//必须实现的：

//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
- (void)centralManagerDidUpdateState:(CBCentralManager *)central;


//其他选择实现的委托中比较重要的：

//找到外设的委托
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI; 
//连接外设成功的委托
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral;
//外设连接失败的委托
- (void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;
//断开外设的委托
- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;
        

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 CBManagerStateUnknown:
            NSLog(@"蓝牙未知状态");
            break;
        case CBManagerStateResetting:
            NSLog(@"正在重置蓝牙");
            break;
        case CBManagerStateUnsupported:
            NSLog(@"蓝牙不支持状态");
            break;
        case CBManagerStateUnauthorized:
            NSLog(@"蓝牙未授权");
            break;
        case CBManagerStatePoweredOff:
            NSLog(@"蓝牙关闭状态");
            break;
        case CBManagerStatePoweredOn:
            NSLog(@"蓝牙开启状态");
            //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;
             */
            [self.manager scanForPeripheralsWithServices:nil options:nil];

            break;
        default:
            break;
    }

}

3 连接外设(connect)

同时可以在此方法中获取外设设备的广播数据 advertisementData,对数据进行转换解析便可得到想要的内容。

//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
            */

            //找到的设备必须持有它，否则CBCentralManager中也不会保存peripheral，那么CBPeripheralDelegate中的方法也不会被调用！！
            [peripherals addObject:peripheral];
            //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]);

}

有一点非常容易出错，请注意

   //找到的设备必须持有它，否则CBCentralManager中也不会保存peripheral，那么CBPeripheralDelegate中的方法也不会被调用！！
    [peripherals addObject:peripheral];

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
    [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];
}