iOS开发蓝牙4.0的框架是CoreBluetooth，本文主要介绍CoreBluetooth的使用，关于本文中的代码片断大多来自github上的一个demo，地址是myz1104/Bluetooth。
在CoreBluetooth中有两个主要的部分,Central和Peripheral，有一点相似Client Server。CBPeripheralManager 做为周边设备是服务器。CBCentralManager做为中心设备是客户端。全部可用的iOS设备能够做为周边（Peripheral）也能够做为中央（Central），但不能够同时既是周边也是中央。
git
通常手机是客户端， 设备（好比手环）是服务器，由于是手机去链接手环这个服务器。周边（Peripheral）是生成或者保存了数据的设备，中央（Central）是使用这些数据的设备。你能够认为周边是一个广播数据的设备，他广播到外部世界说他这儿有数据，而且也说明了能提供的服务。另外一边，中央开始扫描附近有没有服务，若是中央发现了想要的服务，而后中央就会请求链接周边，一旦链接创建成功，两个设备之间就开始交换传输数据了。
除了中央和周边，咱们还要考虑他俩交换的数据结构。这些数据在服务中被结构化，每一个服务由不一样的特征（Characteristics）组成，特征是包含一个单一逻辑值的属性类型。github
首先是建立一个周边数组
_peripheralManager = [[CBPeripheralManager alloc]initWithDelegate:self queue:nil];
接下来它就会响应代理的peripheralManagerDidUpdateState方法，能够得到peripheral的状态等信息，服务器
- (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral
{
switch (peripheral.state)
{
case CBPeripheralManagerStatePoweredOn:
{
[self setupService];
}
break;
default:
{
NSLog(@"Peripheral Manager did change state");
}
break;
}
}
当发现周边设备的蓝牙是能够的时候，这就须要去准备你须要广播给其余中央设备的服务和特征了，这里经过调用setupService方法来实现。
每个服务和特征都须要用一个UUID（unique identifier）去标识，UUID是一个16bit或者128bit的值。若是你要建立你的中央-周边App，你须要建立你本身的128bit的UUID。你必需要肯定你本身的UUID不能和其余已经存在的服务冲突。若是你正要建立一个本身的设备，须要实现标准委员会需求的UUID；若是你只是建立一个中央-周边App，我建议你打开Mac OS X的Terminal.app，用uuidgen命令生成一个128bit的UUID。你应该用该命令两次，生成两个UUID，一个是给服务用的，一个是给特征用的。而后，你须要添加他们到中央和周边App中。如今，在view controller的实现以前，咱们添加如下的代码：数据结构
static NSString * const kServiceUUID = @"1C85D7B7-17FA-4362-82CF-85DD0B76A9A5";
static NSString * const kCharacteristicUUID = @"7E887E40-95DE-40D6-9AA0-36EDE2BAE253";
下面就是setupService方法app
- (void)setupService
{
CBUUID *characteristicUUID = [CBUUID UUIDWithString:kCharacteristicUUID];
self.customCharacteristic = [[CBMutableCharacteristic alloc] initWithType:characteristicUUID properties:CBCharacteristicPropertyNotify value:nil permissions:CBAttributePermissionsReadable];
CBUUID *serviceUUID = [CBUUID UUIDWithString:kServiceUUID];
self.customService = [[CBMutableService alloc] initWithType:serviceUUID primary:YES];
[self.customService setCharacteristics:@[self.customCharacteristic]];
[self.peripheralManager addService:self.customService];
}
当调用了CBPeripheralManager的addService方法后，这里就会响应CBPeripheralManagerDelegate的- (void)peripheralManager:(CBPeripheralManager *)peripheral didAddService:(CBService *)service error:(NSError *)error方法。这个时候就能够开始广播咱们刚刚建立的服务了。框架
- (void)peripheralManager:(CBPeripheralManager *)peripheral didAddService:(CBService *)service error:(NSError *)error
{
if (error == nil)
{
[self.peripheralManager startAdvertising:@{ CBAdvertisementDataLocalNameKey : @"ICServer", CBAdvertisementDataServiceUUIDsKey : @[[CBUUID UUIDWithString:kServiceUUID]] }];
}
}
固然到这里，你已经作完了peripheralManager的工做了，中央设备已经能够接受到你的服务了。不过这是静止的数据，你还能够调用- (BOOL)updateValue:(NSData *)value forCharacteristic:(CBMutableCharacteristic *)characteristic onSubscribedCentrals:(NSArray *)centrals方法能够给中央生成动态数据的地方。async
- (void)sendToSubscribers:(NSData *)data {
if (self.peripheral.state != CBPeripheralManagerStatePoweredOn) {
LXCBLog(@"sendToSubscribers: peripheral not ready for sending state: %d", self.peripheral.state);
return;
}
BOOL success = [self.peripheral updateValue:data
forCharacteristic:self.characteristic
onSubscribedCentrals:nil];
if (!success) {
LXCBLog(@"Failed to send data, buffering data for retry once ready.");
self.pendingData = data;
return;
}
}
central订阅了characteristic的值，当更新值的时候peripheral会调用updateValue: forCharacteristic: onSubscribedCentrals:(NSArray*)centrals去为数组里面的centrals更新对应characteristic的值，在更新事后peripheral为每个central走一遍下面的代理方法ide
- (void)peripheralManager:(CBPeripheralManager *)peripheral central:(CBCentral *)central didSubscribeToCharacteristic:(CBCharacteristic *)characteristic
peripheral接受到一个读或者写的请求时，会响应如下两个代理方法ui
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveReadRequest:(CBATTRequest *)request
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray *)requests
那么如今peripheral就已经建立好了。
建立中央而且链接周边
如今，咱们已经有了一个周边，让咱们建立咱们的中央。中央就是那个处理周边发送来的数据的设备。
self.manager = [[CBCentralManager alloc] initWithDelegate:self queue:dispatch_get_main_queue()];
当Central Manager被初始化，咱们要检查它的状态，以检查运行这个App的设备是否是支持BLE。实现CBCentralManagerDelegate的代理方法：
- (void)centralManagerDidUpdateState:(CBCentralManager *)central
{
switch (central.state)
{
case CBCentralManagerStatePoweredOn:
{
[self.manager scanForPeripheralsWithServices:@[ [CBUUID UUIDWithString:kServiceUUID]]
options:@{CBCentralManagerScanOptionAllowDuplicatesKey : @YES }];
}
break;
default:
{
NSLog(@"Central Manager did change state");
}
break;
}
}
当app的设备是支持蓝牙的时候，须要调用CBCentralManager实例的- (void)scanForPeripheralsWithServices:(NSArray *)serviceUUIDs options:(NSDictionary *)options方法，用来寻找一个指定的服务的peripheral。一旦一个周边在寻找的时候被发现，中央的代理会收到如下回调：
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI
{
NSString *UUID = [peripheral.identifier UUIDString];
NSString *UUID1 = CFBridgingRelease(CFUUIDCreateString(NULL, peripheral.UUID));
NSLog(@"----发现外设----%@%@", UUID,UUID1);
[self.manager stopScan];
if (self.peripheral != peripheral)
{
self.peripheral = peripheral;
NSLog(@"Connecting to peripheral %@", peripheral);
[self.manager connectPeripheral:peripheral options:nil];
}
}
这个时候一个附带着广播数据和信号质量(RSSI-Received Signal Strength Indicator)的周边被发现。这是一个很酷的参数，知道了信号质量，你能够用它去判断远近。任何广播、扫描的响应数据保存在advertisementData 中，能够经过CBAdvertisementData 来访问它。
这个时候你用能够链接这个周边设备了，
[self.manager connectPeripheral:peripheral options:nil];
它会响应下面的代理方法，
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
{
NSLog(@"----成功链接外设----");
[self.peripheral setDelegate:self];
[self.peripheral discoverServices:@[ [CBUUID UUIDWithString:kServiceUUID]]];
}
访问周边的服务
上面的CBCentralManagerDelegate代理会返回CBPeripheral实例，它的- (void)discoverServices:(NSArray *)serviceUUIDs方法就是访问周边的服务了，这个方法会响应CBPeripheralDelegate的方法。
- (void)peripheral:(CBPeripheral *)aPeripheral didDiscoverServices:(NSError *)error
{
NSLog(@"----didDiscoverServices----Error:%@",error);
if (error)
{
NSLog(@"Error discovering service: %@", [error localizedDescription]);
[self cleanup];
return;
}
for (CBService *service in aPeripheral.services)
{
NSLog(@"Service found with UUID: %@", service.UUID);
if ([service.UUID isEqual:[CBUUID UUIDWithString:kServiceUUID]])
{
[self.peripheral discoverCharacteristics:@[[CBUUID UUIDWithString:kCharacteristicUUID],[CBUUID UUIDWithString:kWrriteCharacteristicUUID]] forService:service];
}
}
}
在上面的方法中若是没有error，能够调用discoverCharacteristics方法请求周边去寻找它的服务所列出的特征，它会响应下面的方法
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error
{
if (error)
{
NSLog(@"Error discovering characteristic: %@", [error localizedDescription]);
return;
}
if ([service.UUID isEqual:[CBUUID UUIDWithString:kServiceUUID]])
{
for (CBCharacteristic *characteristic in service.characteristics)
{
NSLog(@"----didDiscoverCharacteristicsForService---%@",characteristic);
if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:kCharacteristicUUID]])
{
[peripheral readValueForCharacteristic:characteristic];
[peripheral setNotifyValue:YES forCharacteristic:characteristic];
}
if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:kWrriteCharacteristicUUID]])
{
writeCharacteristic = characteristic;
}
}
}
}
这个时候peripheral能够调用两个方法，
[peripheral readValueForCharacteristic:characteristic]这个是读特征值的，会响应- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error；
[peripheral setNotifyValue:YES forCharacteristic:characteristic];会响应- (void)peripheral:(CBPeripheral *)peripheral didUpdateNotificationStateForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error；
- (void)peripheral:(CBPeripheral *)peripheral didUpdateNotificationStateForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
{
if (error)
{
NSLog(@"Error changing notification state: %@", error.localizedDescription);
}
// Exits if it's not the transfer characteristic
if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:kCharacteristicUUID]] )
{
// Notification has started
if (characteristic.isNotifying)
{
NSLog(@"Notification began on %@", characteristic);
[peripheral readValueForCharacteristic:characteristic];
}
else
{ // Notification has stopped
// so disconnect from the peripheral
NSLog(@"Notification stopped on %@. Disconnecting", characteristic);
[self.manager cancelPeripheralConnection:self.peripheral];
}
}
}
- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
{
NSLog(@"----Value---%@",characteristic.value);
if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:kCharacteristicUUID]])
{
if (writeCharacteristic)
{
Byte ACkValue[3] = {0};
ACkValue[0] = 0xe0; ACkValue[1] = 0x00; ACkValue[2] = ACkValue[0] + ACkValue[1];
NSData *data = [NSData dataWithBytes:&ACkValue length:sizeof(ACkValue)];
[self.peripheral writeValue:data
forCharacteristic:writeCharacteristic
type:CBCharacteristicWriteWithoutResponse];
}
}
}
在上面的方法中，- (void)writeValue:(NSData *)data forCharacteristic:(CBCharacteristic *)characteristic type:(CBCharacteristicWriteType)type是一个对周边设备写数据的方法，它会响应下面的方法
- (void)peripheral:(CBPeripheral *)peripheral didWriteValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
{
NSLog(@"---didWriteValueForCharacteristic-----");
if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:kWrriteCharacteristicUUID]])
{
NSLog(@"----value更新----");
}
}
这样，中央设备也实现了读写数据的功能了。
另外，github上有一个封装的第三方开源蓝牙框架，地址是kickingvegas/YmsCoreBluetooth