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 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)BOOLisScanningNS_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:
typedefNS_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:(nullableid)delegate queue:(nullabledispatch_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:(nullableid)delegate queue:(nullabledispatch_queue_t)queue options:(nullableNSDictionary *)options;
//根据获取所有已知设备- (NSArray *)retrievePeripheralsWithIdentifiers:(NSArray *)identifiers;//根据服务id获取所有连接的设备- (NSArray *)retrieveConnectedPeripheralsWithServices:(NSArray *)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:(nullableNSArray *)serviceUUIDs options:(nullableNSDictionary *)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 *)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:(nullableNSDictionary *)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 *)centraldidConnectPeripheral:(CBPeripheral *)peripheral;//连接外设失败- (void)centralManager:(CBCentralManager *)centraldidFailToConnectPeripheral:(CBPeripheral *)peripheralerror:(nullable NSError *)error;//断开外设连接- (void)centralManager:(CBCentralManager *)centraldidDisconnectPeripheral:(CBPeripheral *)peripheralerror:(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 *)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 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)BOOLisAdvertising;//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:(nullableid)delegate queue:(nullabledispatch_queue_t);- (instancetype)initWithDelegate:(nullableid)delegate queue:(nullabledispatch_queue_t)queue options:(nullableNSDictionary *)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:(nullableNSDictionary *)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:(nullableNSArray *)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 *)peripheralwillRestoreState:(NSDictionary *)dict;//开始发送广播时调用的方法- (void)peripheralManagerDidStartAdvertising:(CBPeripheralManager *)peripheralerror:(nullable NSError *)error;//添加服务调用的回调- (void)peripheralManager:(CBPeripheralManager *)peripheraldidAddService:(CBService *)serviceerror:(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 *)peripheralcentral:(CBCentral *)centraldidSubscribeToCharacteristic:(CBCharacteristic *)characteristic;//取消订阅一个特征值时调用的方法- (void)peripheralManager:(CBPeripheralManager *)peripheralcentral:(CBCentral *)centraldidUnsubscribeFromCharacteristic:(CBCharacteristic *)characteristic;//收到读请求时触发的方法- (void)peripheralManager:(CBPeripheralManager *)peripheraldidReceiveReadRequest:(CBATTRequest *)request;//收到写请求时触发的方法- (void)peripheralManager:(CBPeripheralManager *)peripheraldidReceiveWriteRequests:(NSArray *)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)NSUIntegermaximumUpdateValueLength;
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 delegate;//外设name@property(retain,readonly,nullable)NSString*name;//信号强度@property(retain,readonly,nullable)NSNumber*RSSINS_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 *services;//获取当前信号强度- (void)readRSSI;//根据服务UUID寻找服务对象- (void)discoverServices:(nullableNSArray *)serviceUUIDs;//在服务对象UUID数组中寻找特定服务- (void)discoverIncludedServices:(nullableNSArray *)includedServiceUUIDs forService:(CBService *)service;//在一个服务中寻找特征值- (void)discoverCharacteristics:(nullableNSArray *)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)typeNS_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 *)peripheraldidModifyServices:(NSArray *)invalidatedServices NS_AVAILABLE(NA,7_0);//信号强度改变时调用的方法- (void)peripheralDidUpdateRSSI:(CBPeripheral *)peripheralerror:(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 *)peripheraldidReadRSSI:(NSNumber *)RSSIerror:(nullable NSError *)error NS_AVAILABLE(NA,8_0);//发现服务时调用的方法- (void)peripheral:(CBPeripheral *)peripheraldidDiscoverServices:(nullable NSError *)error;//在服务中发现子服务回调的方法- (void)peripheral:(CBPeripheral *)peripheraldidDiscoverIncludedServicesForService:(CBService *)serviceerror:(nullable NSError *)error;//发现服务的特征值后回调的方法- (void)peripheral:(CBPeripheral *)peripheraldidDiscoverCharacteristicsForService:(CBService *)serviceerror:(nullable NSError *)error;//特征值更新时回调的方法- (void)peripheral:(CBPeripheral *)peripheraldidUpdateValueForCharacteristic:(CBCharacteristic *)characteristicerror:(nullable NSError *)error;//向特征值写数据时回调的方法- (void)peripheral:(CBPeripheral *)peripheraldidWriteValueForCharacteristic:(CBCharacteristic *)characteristicerror:(nullable NSError *)error;//特征值的通知设置改变时触发的方法- (void)peripheral:(CBPeripheral *)peripheraldidUpdateNotificationStateForCharacteristic:(CBCharacteristic *)characteristicerror:(nullable NSError *)error;//发现特征值的描述信息触发的方法- (void)peripheral:(CBPeripheral *)peripheraldidDiscoverDescriptorsForCharacteristic:(CBCharacteristic *)characteristicerror:(nullable NSError *)error;//特征的描述值更新时触发的方法- (void)peripheral:(CBPeripheral *)peripheraldidUpdateValueForDescriptor:(CBDescriptor *)descriptorerror:(nullable NSError *)error;//写描述信息时触发的方法- (void)peripheral:(CBPeripheral *)peripheraldidWriteValueForDescriptor:(CBDescriptor *)descriptorerror:(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)BOOLisPrimary;//包含的自服务@property(retain,readonly,nullable)NSArray *includedServices;//服务中的特征值@property(retain,readonly,nullable)NSArray *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 *descriptors;//是否是当前广播的特征@property(readonly)BOOLisBroadcasted;//是否是正在通知的特征@property(readonly)BOOLisNotifying;
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;
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