ios设备app作为蓝牙外设端

苹果手机可以作为蓝牙外设端，被蓝牙中央端来扫描连接交互数据，实现模拟蓝牙外设硬件。通过阅读CoreBluetooth库，可以找到一个CBPeripheralManager的类，该类主要的作用就是允许你来管理发布services，把这些services广告给其他的设备。如果想详细了解该类的属性和方法，建议去看看CoreBluetooth/CBPeripheralManager.h。
下面来模拟一个简单的蓝牙外设端。
准备工作
CBUUID *serviceUUID;
CBUUID *characteristicUUID;
NSData *characteristicValue;
NSString *localName;
NSArray *serviceUUIDs;

上面中，serviceUUID为给外设配置的服务的UUID，可以有多个，characteristicUUID为给service添加的特征的UUID，也可以有多个，可自定义可读可写等等属性.characteristicValue为characteristic的值,localName和serviceUUIDs分别为键CBAdvertisementDataLocalNameKey和CBAdvertisementDataServiceUUIDsKey对应的value。由于作为外设端时发送广播包，广播包中提供包含着两个键值对，如果有另外的键值对想要发送，例如CBAdvertisementDataServiceDataKey，会出现错误。
开始
首先要导入蓝牙库
#import <CoreBluetooth/CoreBluetooth.h>
遵守协议
 @interface viewController()<CBPeripheralManagerDelegate>

创建peripheralManager对象
self.peripheralManager = [[CBPeripheralManager alloc] initWithDelegate:self queue:nil];//nil表示在主线程中执行。

创建了peripheralManager对象后会自动调用回调方法didUpdateState
- (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral {
if (peripheral.state != CBPeripheralManagerStatePowerOn) {
return;
}
}
给外设配置服务和特征
- (void)configServiceAndCharacteristicForPeripheral {
CBMutableCharacteristic *writeReadCharacteristic = [[CBMutableCharacteristic alloc] initWithType:characteristicUUID properties:CBCharacteristicPropertyWrite | CBCharacteristicPropertyRead value:nil permissions:CBAttributePermissionsReadEncryptionRequired | CBAttributePermissionsWriteEncryptionRequired];
CBMutableService *service = [[CBMutableService alloc] initWithType:serviceUUID primary:YES];
[service setCharacteristics:@[writeReadCharacteristic]];
[self.peripheralManager addService:service];
}
调用上面的方法时，会监听didAddService:
- (void)peripheralManager:(CBPeripheralManager *)peripheral didAddService:(CBService *)service error:(NSError *)error {
}
开始广播
[self.peripheralManager startAdvertising:@{CBAdvertisementDataServiceUUIDsKey:serviceUUIDs,CBAdvertisementDataNameKey:localName}];

调用上 面方法时，会监听DidStartAdvertising:
- (void)peripheralManagerDidStartAdvertising:(CBPeripheralManager *)peripheral error:(NSError *)error {
}
当中央端连接上了此设备并订阅了特征时会回调 didSubscribeToCharacteristic:
- (void)peripheralManager:(CBPeripheralManager *)peripheral central:(CBCentral *)central didSubscribeToCharacteristic:(CBCharacteristic *)characteristic {
[self.peripheralManager updateValue:characteristicValue forCharacteristic:characteristic onSubscribedCentrals:nil];
}
当中央端取消订阅时会调用didUnsubscribeFromCharacteristic:
- (void)peripheralManager:(CBPeripheralManager *)peripheral central:(CBCentral *)central didUnsubscribeFromCharacteristic:(CBCharacteristic *)characteristic {
}
当接收到中央端读的请求时会调用didReceiveReadRequest:
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveReadRequest:(CBATTRequest *)request {
if (request.characteristic.properties & CBCharacteristicPropertyRead) {
NSData *data = request.characteristic.value;
[request setValue:data];
[self.peripheralManager respondToRequest:request withResult:CBATTErrorSuccess];
} else {
[self.peripheralManager respondToRequest:request withResult:CBATTErrorReadNotPermitted];
}
}
当接收到中央端写的请求时会调用didReceiveWriteRequest:
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray<CBATTRequest *> *)requests {
CBATTRequest *request = requests[0];
if (request.characteristic.properties & CBCharacteristicPropertyWrite) {
CBMutableCharacteristic *c = (CBMutableCharacteristic *)request.characteristic;
c.value = request.value;
[self.peripheralManager respondToRequest:request withResult:CBATTErrorSuccess];
} else {
[self.peripheralManager respondToRequest:request withResult:CBATTErrorWriteNotPermitted];
}
}
手机app可以作为一个蓝牙外设端来模拟外设硬件，但广播包里的数据只能包含localName和serviceUUID，相对于外设硬件来说还是有一些不足之处。