iOS开发之蓝牙通讯
iOS开发之蓝牙通讯
一、引言
蓝牙是设备近距离通信的一种方便手段,在iPhone引入蓝牙4.0后,设备之间的通讯变得更加简单。相关的蓝牙操作由专门的CoreBluetooth.framework进行统一管理。通过蓝牙进行通讯交互分为两方,一方为中心设备central,一方为外设peripheral,外设通过广播的方式向外发送信息,中心设备检索到外设发的广播信息,可以进行配对连接,进而进行数据交互。
二、中心设备CBCentralManager
CBCentralManager是管理中心设备的管理类,其中重要方法如下:
//设置中心设备代理
@property(assign, nonatomic, nullable) id<CBCentralManagerDelegate> delegate;
//中心设备当前状态
@property(readonly) CBCentralManagerState state;
//中心设备是否正在扫描
@property(readonly) BOOL isScanning NS_AVAILABLE(NA, 9_0);
其中state是一个枚举,有关蓝牙是否可用的状态如下:
typedef NS_ENUM(NSInteger, CBCentralManagerState) {
//状态未知
CBCentralManagerStateUnknown = 0,
//连接断开 即将重置
CBCentralManagerStateResetting,
//该平台不支持蓝牙
CBCentralManagerStateUnsupported,
//未授权蓝牙使用
CBCentralManagerStateUnauthorized,
//蓝牙关闭
CBCentralManagerStatePoweredOff,
//蓝牙正常开启
CBCentralManagerStatePoweredOn,
};
下面这些方法用于初始化管理中心:
//初始化方法
//设置的代理需要遵守CBCentralManagerDelegate协议
//queue可以设置蓝牙扫描的线程 传入nil则为在主线程中进行
- (instancetype)initWithDelegate:(nullable id<CBCentralManagerDelegate>)delegate
queue:(nullable dispatch_queue_t)queue;
//此方法同上 在options字典中用于进行一些管理中心的初始化属性设置
//字典中支持的键值如下
/*
NSString * const CBCentralManagerOptionShowPowerAlertKey 对应一个NSNumber类型的bool值,用于设置是否在关闭蓝牙时弹出用户提示
NSString * const CBCentralManagerOptionRestoreIdentifierKey 对应一个NSString对象,设置管理中心的标识符ID
*/
- (instancetype)initWithDelegate:(nullable id<CBCentralManagerDelegate>)delegate
queue:(nullable dispatch_queue_t)queue
options:(nullable NSDictionary<NSString *, id> *)options;
//根据获取所有已知设备
- (NSArray<CBPeripheral *> *)retrievePeripheralsWithIdentifiers:(NSArray<NSUUID *> *)identifiers;
//根据服务id获取所有连接的设备
- (NSArray<CBPeripheral *> *)retrieveConnectedPeripheralsWithServices:(NSArray<CBUUID *> *)serviceUUIDs;
在初始化管理中心完成后,会回调代理中的如下方法,我们必须实现如下方法:
//这个方法中可以获取到管理中心的状态
- (void)centralManagerDidUpdateState:(CBCentralManager *)central;
如果上面方法中管理中心状态为蓝牙可用,可以通过下面方法开启扫描外设:
//serviceUUIDs用于扫描一个特点ID的外设 options用于设置一些扫描属性 键值如下
/*
//是否允许重复扫描 对应NSNumber的bool值,默认为NO,会自动去重
NSString *const CBCentralManagerScanOptionAllowDuplicatesKey;
//要扫描的设备UUID 数组 对应NSArray
NSString *const CBCentralManagerScanOptionSolicitedServiceUUIDsKey;
*/
- (void)scanForPeripheralsWithServices:(nullable NSArray<CBUUID *> *)serviceUUIDs options:(nullable NSDictionary<NSString *, id> *)options;
//停止扫描外设
- (void)stopScan;
扫描的结果会在如下代理方法中回掉:
//peripheral 扫描到的外设
//advertisementData是外设发送的广播数据
//RSSI 是信号强度
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary<NSString *, id> *)advertisementData RSSI:(NSNumber *)RSSI;
扫描到外设后,通过下面方法可以连接一个外设:
/*
options中可以设置一些连接设备的初始属性键值如下
//对应NSNumber的bool值,设置当外设连接后是否弹出一个警告
NSString *const CBConnectPeripheralOptionNotifyOnConnectionKey;
//对应NSNumber的bool值,设置当外设断开连接后是否弹出一个警告
NSString *const CBConnectPeripheralOptionNotifyOnDisconnectionKey;
//对应NSNumber的bool值,设置当外设暂停连接后是否弹出一个警告
NSString *const CBConnectPeripheralOptionNotifyOnNotificationKey;
*/
- (void)connectPeripheral:(CBPeripheral *)peripheral options:(nullable NSDictionary<NSString *, id> *)options;
//取消一个外设的连接
- (void)cancelPeripheralConnection:(CBPeripheral *)peripheral;
调用过连接外设的方法后,会回掉如下代理方法:
//连接外设成功
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral;
//连接外设失败
- (void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(nullable NSError *)error;
//断开外设连接
- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(nullable NSError *)error;
当管理中心恢复时会调用如下代理:
//dict中会传入如下键值对
/*
//恢复连接的外设数组
NSString *const CBCentralManagerRestoredStatePeripheralsKey;
//恢复连接的服务UUID数组
NSString *const CBCentralManagerRestoredStateScanServicesKey;
//恢复连接的外设扫描属性字典数组
NSString *const CBCentralManagerRestoredStateScanOptionsKey;
*/
- (void)centralManager:(CBCentralManager *)central willRestoreState:(NSDictionary<NSString *, id> *)dict;
三、外设CBPeripheralManager
从上面我们知道,中心设备是用来扫描周围的外设,两台设备的通讯中,必须有一个充当中心设备,一个充当外设,外设是由CBPeripheralManager进行管理,主要方法如下:
//设置外设管理中心代理
@property(assign, nonatomic, nullable) id<CBPeripheralManagerDelegate> delegate;
//外设状态 枚举如中心设备
@property(readonly) CBPeripheralManagerState state;
//是否正在发送广播
@property(readonly) BOOL isAdvertising;
//用户的授权状态
+ (CBPeripheralManagerAuthorizationStatus)authorizationStatus;
//初始化并设置代理 参数的具体含义与中心设备管理中心
- (instancetype)initWithDelegate:(nullable id<CBPeripheralManagerDelegate>)delegate
queue:(nullable dispatch_queue_t);
- (instancetype)initWithDelegate:(nullable id<CBPeripheralManagerDelegate>)delegate
queue:(nullable dispatch_queue_t)queue
options:(nullable NSDictionary<NSString *, id> *)options;
//开始发送广播
//advertisementData中可以发送的数据有约定 如下
/*
对应设置NSString类型的广播名
NSString *const CBAdvertisementDataLocalNameKey;
外设制造商的NSData数据
NSString *const CBAdvertisementDataManufacturerDataKey;
外设制造商的CBUUID数据
NSString *const CBAdvertisementDataServiceDataKey;
服务的UUID与其对应的服务数据字典数组
NSString *const CBAdvertisementDataServiceUUIDsKey;
附加服务的UUID数组
NSString *const CBAdvertisementDataOverflowServiceUUIDsKey;
外设的发送功率 NSNumber类型
NSString *const CBAdvertisementDataTxPowerLevelKey;
外设是否可以连接
NSString *const CBAdvertisementDataIsConnectable;
服务的UUID数组
NSString *const CBAdvertisementDataSolicitedServiceUUIDsKey;
*/
- (void)startAdvertising:(nullable NSDictionary<NSString *, id> *)advertisementData;
//停止发送广播
- (void)stopAdvertising;
//设置一个连接的具体central设备的延时 枚举如下
/*
typedef NS_ENUM(NSInteger, CBPeripheralManagerConnectionLatency) {
CBPeripheralManagerConnectionLatencyLow = 0,
CBPeripheralManagerConnectionLatencyMedium,
CBPeripheralManagerConnectionLatencyHigh
} NS_ENUM_AVAILABLE(NA, 6_0);
*/
- (void)setDesiredConnectionLatency:(CBPeripheralManagerConnectionLatency)latency forCentral:(CBCentral *)central;
//添加一个服务
- (void)addService:(CBMutableService *)service;
//移除一个服务
- (void)removeService:(CBMutableService *)service;
//移除所有服务
- (void)removeAllServices;
//响应中心设备的读写请求
- (void)respondToRequest:(CBATTRequest *)request withResult:(CBATTError)result;
//更新一个连接中心设备的订阅特征值
- (BOOL)updateValue:(NSData *)value forCharacteristic:(CBMutableCharacteristic *)characteristic onSubscribedCentrals:(nullable NSArray<CBCentral *> *)centrals;
外设代理的相关方法如下:
//这个方法是必须实现的 状态可用后可以发送广播
- (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral;
//连接回复时调用的方法 和centralManager类似
- (void)peripheralManager:(CBPeripheralManager *)peripheral willRestoreState:(NSDictionary<NSString *, id> *)dict;
//开始发送广播时调用的方法
- (void)peripheralManagerDidStartAdvertising:(CBPeripheralManager *)peripheral error:(nullable NSError *)error;
//添加服务调用的回调
- (void)peripheralManager:(CBPeripheralManager *)peripheral didAddService:(CBService *)service error:(nullable NSError *)error;
//当一个central设备订阅一个特征值时调用的方法
- (void)peripheralManager:(CBPeripheralManager *)peripheral central:(CBCentral *)central didSubscribeToCharacteristic:(CBCharacteristic *)characteristic;
//取消订阅一个特征值时调用的方法
- (void)peripheralManager:(CBPeripheralManager *)peripheral central:(CBCentral *)central didUnsubscribeFromCharacteristic:(CBCharacteristic *)characteristic;
//收到读请求时触发的方法
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveReadRequest:(CBATTRequest *)request;
//收到写请求时触发的方法
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray<CBATTRequest *> *)requests;
//外设准备更新特征值时调用的方法
- (void)peripheralManagerIsReadyToUpdateSubscribers:(CBPeripheralManager *)peripheral;
四、中心设备与外设对象CBCentral与CBPeripheral
上面介绍了中心设备管理类与外设管理类,这些类用于将设备连接建立起来,器具的数据交换的服务和一些信息则是在对应的设备对象中。
1、中心设备 CBCentral属性与方法
//设备UUID
@property(readonly, nonatomic) NSUUID *identifier;
//中心设备最大接收的数据长度
@property(readonly, nonatomic) NSUInteger maximumUpdateValueLength;
2、外设CAPeripheral属性与方法
外设对象要比中心对象复杂的多,当centralManager连接到外设后,需要通过外设对象的代理方法进行数据交互,其中主要方法属性如下:
//设置代理
@property(assign, nonatomic, nullable) id<CBPeripheralDelegate> delegate;
//外设name
@property(retain, readonly, nullable) NSString *name;
//信号强度
@property(retain, readonly, nullable) NSNumber *RSSI NS_DEPRECATED(NA, NA, 5_0, 8_0);
//外设状态
/*
typedef NS_ENUM(NSInteger, CBPeripheralState) {
CBPeripheralStateDisconnected = 0,//未连接
CBPeripheralStateConnecting,//正在链接
CBPeripheralStateConnected,//已经连接
CBPeripheralStateDisconnecting NS_AVAILABLE(NA, 9_0),//正在断开连接
} NS_AVAILABLE(NA, 7_0);
*/
@property(readonly) CBPeripheralState state;
//所有的服务数组
@property(retain, readonly, nullable) NSArray<CBService *> *services;
//获取当前信号强度
- (void)readRSSI;
//根据服务UUID寻找服务对象
- (void)discoverServices:(nullable NSArray<CBUUID *> *)serviceUUIDs;
//在服务对象UUID数组中寻找特定服务
- (void)discoverIncludedServices:(nullable NSArray<CBUUID *> *)includedServiceUUIDs forService:(CBService *)service;
//在一个服务中寻找特征值
- (void)discoverCharacteristics:(nullable NSArray<CBUUID *> *)characteristicUUIDs forService:(CBService *)service;
//从一个特征中读取数据
- (void)readValueForCharacteristic:(CBCharacteristic *)characteristic;
//写数据的最大长度
//type枚举如下
/*
typedef NS_ENUM(NSInteger, CBCharacteristicWriteType) {
CBCharacteristicWriteWithResponse = 0,//写数据并且接收成功与否回执
CBCharacteristicWriteWithoutResponse,//写数据不接收回执
};
*/
- (NSUInteger)maximumWriteValueLengthForType:(CBCharacteristicWriteType)type NS_AVAILABLE(NA, 9_0);
//向某个特征中写数据
- (void)writeValue:(NSData *)data forCharacteristic:(CBCharacteristic *)characteristic type:(CBCharacteristicWriteType)type;
//为制定的特征值设置监听通知
- (void)setNotifyValue:(BOOL)enabled forCharacteristic:(CBCharacteristic *)characteristic;
//寻找特征值的描述
- (void)discoverDescriptorsForCharacteristic:(CBCharacteristic *)characteristic;
//读取特征的描述值
- (void)readValueForDescriptor:(CBDescriptor *)descriptor;
//写特征的描述值
- (void)writeValue:(NSData *)data forDescriptor:(CBDescriptor *)descriptor;
外设的代理方法如下:
//外设名称更改时回调的方法
- (void)peripheralDidUpdateName:(CBPeripheral *)peripheral NS_AVAILABLE(NA, 6_0);
//外设服务变化时回调的方法
- (void)peripheral:(CBPeripheral *)peripheral didModifyServices:(NSArray<CBService *> *)invalidatedServices NS_AVAILABLE(NA, 7_0);
//信号强度改变时调用的方法
- (void)peripheralDidUpdateRSSI:(CBPeripheral *)peripheral error:(nullable NSError *)error NS_DEPRECATED(NA, NA, 5_0, 8_0);
//读取信号强度回调的方法
- (void)peripheral:(CBPeripheral *)peripheral didReadRSSI:(NSNumber *)RSSI error:(nullable NSError *)error NS_AVAILABLE(NA, 8_0);
//发现服务时调用的方法
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(nullable NSError *)error;
//在服务中发现子服务回调的方法
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverIncludedServicesForService:(CBService *)service error:(nullable NSError *)error;
//发现服务的特征值后回调的方法
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(nullable NSError *)error;
//特征值更新时回调的方法
- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(nullable NSError *)error;
//向特征值写数据时回调的方法
- (void)peripheral:(CBPeripheral *)peripheral didWriteValueForCharacteristic:(CBCharacteristic *)characteristic error:(nullable NSError *)error;
//特征值的通知设置改变时触发的方法
- (void)peripheral:(CBPeripheral *)peripheral didUpdateNotificationStateForCharacteristic:(CBCharacteristic *)characteristic error:(nullable NSError *)error;
//发现特征值的描述信息触发的方法
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverDescriptorsForCharacteristic:(CBCharacteristic *)characteristic error:(nullable NSError *)error;
//特征的描述值更新时触发的方法
- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForDescriptor:(CBDescriptor *)descriptor error:(nullable NSError *)error;
//写描述信息时触发的方法
- (void)peripheral:(CBPeripheral *)peripheral didWriteValueForDescriptor:(CBDescriptor *)descriptor error:(nullable NSError *)error;
五、服务对象CBService
服务对象是用来管理外设提供的一些数据服务的,其中属性如下:
//对应的外设
@property(assign, readonly, nonatomic) CBPeripheral *peripheral;
//是否是初等服务
@property(readonly, nonatomic) BOOL isPrimary;
//包含的自服务
@property(retain, readonly, nullable) NSArray<CBService *> *includedServices;
//服务中的特征值
@property(retain, readonly, nullable) NSArray<CBCharacteristic *> *characteristics;
六、服务的特征值CBCharacteristic
通过绑定服务中的特征值来进行数据的读写操作,其中属性如下:
//对应的服务对象
@property(assign, readonly, nonatomic) CBService *service;
//特征值的属性 枚举如下
/*
typedef NS_OPTIONS(NSUInteger, CBCharacteristicProperties) {
CBCharacteristicPropertyBroadcast,//允许广播特征
CBCharacteristicPropertyRead,//可读属性
CBCharacteristicPropertyWriteWithoutResponse,//可写并且接收回执
CBCharacteristicPropertyWrite,//可写属性
CBCharacteristicPropertyNotify,//可通知属性
CBCharacteristicPropertyIndicate,//可展现的特征值
CBCharacteristicPropertyAuthenticatedSignedWrites,//允许签名的特征值写入
CBCharacteristicPropertyExtendedProperties,
CBCharacteristicPropertyNotifyEncryptionRequired,
CBCharacteristicPropertyIndicateEncryptionRequired
};
*/
@property(readonly, nonatomic) CBCharacteristicProperties properties;
//特征值的数据
@property(retain, readonly, nullable) NSData *value;
//特征值的描述
@property(retain, readonly, nullable) NSArray<CBDescriptor *> *descriptors;
//是否是当前广播的特征
@property(readonly) BOOL isBroadcasted;
//是否是正在通知的特征
@property(readonly) BOOL isNotifying;
七、读写请求对象CBATTRequest
服务对象是外设向中心设备提供的相关数据服务,获取到相应服务后,中心设备可以进行读写请求,读写对象属性如下:
//对应的中心设备
@property(readonly, nonatomic) CBCentral *central;
//对应的特征值
@property(readonly, nonatomic) CBCharacteristic *characteristic;
//读写数据值
@property(readwrite, copy, nullable) NSData *value;