iOS: 将数据添加到 BLE 特征抛出错误要求只读特征

Question

我有一个 iOS BLE 服务，可以通告并可以连接，但现在我想为外围设备添加一个特性。我想我只是将一个新的 NSData 对象添加到值属性以创建特征，但是每当我在外围管理器上调用 addService 时，我都会收到此错误：

2015-09-24 09:02:59.456 peripheral[459:27589] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Characteristics with cached values must be read-only'

我添加特征的方法是这样的：

- (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral{
    if (peripheral.state == CBPeripheralManagerStatePoweredOn) {
        _shareService = [[CBMutableService alloc] initWithType:_serviceUUID primary:YES];
        _notifyUUID = [CBUUID UUIDWithString:@"F098FDEF-B82C-43F1-8BFB-18757743BA10"];
        _notificationCharacteristic = [[CBMutableCharacteristic alloc] initWithType:_notifyUUID
                                                                         properties:CBCharacteristicPropertyNotify
                                                                              value:[@"Some Data" dataUsingEncoding:NSUTF16StringEncoding]
                                                                        permissions:CBAttributePermissionsReadable];

        [_shareService setCharacteristics:@[_notificationCharacteristic]];

        [_pMgr addService:_shareService];

        [self startAdvertising];

    }
}

虽然当我将价值项目更改为零时，它再次宣传正常。我确定我遗漏了一些简单的东西，但我对 iOS 还是很陌生，所以任何帮助都会很棒。谢谢！

Answer 1

来自 CBMutableCharacteristic 初始化方法的文档 -

value - The characteristic value to be cached. If nil, the value is dynamic and will be requested on demand.

这意味着如果您在创建 CBMutableCharacteristic 时指定了一个非零值，那么它就是一个 'cached characteristic' 并且正如错误消息所说，您以后无法更改该值。在创建 CBMutableCharacteristic 时指定 nil - 您在 didReceiveReadRequest CBPeripheralManagerDelegate 方法中请求时提供值。

iOS: 将数据添加到 BLE 特征抛出错误要求只读特征

iOS: Adding data to a BLE characteristic throwing error asking for read-only characteristic

objective-c

ios

bluetooth-lowenergy