ios – CoreBlueTooth：即使将数据写入可写特征也会出错

我使用CoreBluetooth框架写入Peripheral的一个可写特性.我在中心实现“didWriteValueForCharacteristic：error：”委托,它总是让我失误.虽然我收到了外围设备的数据.

Error Domain=CBErrorDomain Code=0 "UnkNown error." UserInfo=0x166762e0 {NSLocalizedDescription=UnkNown error.}

在我的代码中,我的self.data是一个带有3个键和值的NSDictionary.

// Central

- (void)centralManagerDidUpdateState:(CBCentralManager *)iCentral {
    if (iCentral.state != CBCentralManagerStatePoweredOn) {
        return;
    }

    [self.centralManager scanForperipheralsWithServices:self.peripheralservices options:@{ CBCentralManagerScanoptionAllowDuplicatesKey : @YES}];
}


- (void)centralManager:(CBCentralManager *)central diddiscoverPeripheral:(CBPeripheral *)iPeripheral advertisementData:(NSDictionary *)iAdvertisementData RSSI:(NSNumber *)iRSSI {
    if (self.discoveredPeripheral != iPeripheral) {
        // Save a local copy of the peripheral,so CoreBluetooth doesn't get rid of it
        self.discoveredPeripheral = iPeripheral;

        // Connect to the discovered peripheral
        [self.centralManager connectPeripheral:iPeripheral options:nil];
    }
}

- (void)centralManager:(CBCentralManager *)central diddiscoverPeripheral:(CBPeripheral *)iPeripheral advertisementData:(NSDictionary *)iAdvertisementData RSSI:(NSNumber *)iRSSI {
    if (self.discoveredPeripheral != iPeripheral) {
        // Save a local copy of the peripheral,so CoreBluetooth doesn't get rid of it
        self.discoveredPeripheral = iPeripheral;

        // Connect to the discovered peripheral
        [self.centralManager connectPeripheral:iPeripheral options:nil];
    }
}


// We've connected to the peripheral,Now we need to discover the services and characteristics to find the 'writeable' characteristic.
- (void)centralManager:(CBCentralManager *)iCentral didConnectPeripheral:(CBPeripheral *)iPeripheral {
    // Stop scanning
    [self.centralManager stopScan];

    // Make sure we get the discovery callbacks
    iPeripheral.delegate = self;

    // Search only for services that match our UUID
    [iPeripheral discoverServices:self.peripheralservices];
}


- (void)peripheral:(CBPeripheral *)iPeripheral diddiscoverServices:(NSError *)iError {
    if (iError) {
        [self cleanup];
        return;
    }

    // Loop through the newly filled peripheral.services array,just in case there's more than one.
    for (CBService *service in iPeripheral.services) {
        [iPeripheral discovercharacteristics:@[self.writeableCharactersticsUUID] forService:service];
    }
}


// Write the data into peripheral's characterstics
- (void)peripheral:(CBPeripheral *)iPeripheral diddiscovercharacteristicsForService:(CBService *)iService error:(NSError *)iError {
    if (iError) {
        [self cleanup];

        return;
    }

    // Find out the writable characterstics
    for (CBCharacteristic *characteristic in iService.characteristics) {
        if ([characteristic.UUID isEqual:self.writeableCharactersticsUUID]) {
            NSData *dataToWrite = [NSJSONSerialization dataWithJSONObject:self.data options:0 error:nil];
            NSInteger dataSize = [[NSByteCountFormatter stringFromByteCount:dataToWrite.length countStyle:NSByteCountFormatterCountStyleFile] integerValue];
            if (dataSize > 130) {
                NSLog(@"Cannot send more than 130 bytes");
                return;
            }

            [self.discoveredPeripheral writeValue:dataToWrite forCharacteristic:self.centralWriteableCharacteristic type:CBCharacteristicWriteWithResponse];

            break;
        }
    }
}


- (void)peripheral:(CBPeripheral *)iPeripheral didWriteValueForCharacteristic:(CBCharacteristic *)iCharacteristic error:(NSError *)iError {
    NSLog(@"Error = %@",iError);
}


- (void)cleanup {
    // Don't do anything if we're not connected
    if (self.discoveredPeripheral.state != CBperipheralstateConnected) {
        return;
    }

    // If we've got this far,we're connected,but we're not subscribed,so we just disconnect
    [self.centralManager cancelPeripheralConnection:self.discoveredPeripheral];
}


// Peripheral

- (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)iPeripheral {
    if (iPeripheral.state != CBPeripheralManagerStatePoweredOn) {
        return;
    }

    CBMutableCharacteristic *characteristic = [[CBMutableCharacteristic alloc] initWithType:iCID properties:CBCharacteristicPropertyWrite value:nil permissions:CBAttributePermissionsWriteable];

    CBMutableService *writableService = [[CBMutableService alloc] initWithType:iServiceId primary:YES];
    writableService.characteristics = @[characteristic];

    //[self.peripheralManager removeAllServices];
    [self.peripheralManager addService:writableService];
    [self.peripheralManager startAdvertising:@{ CBAdvertisementDataServiceUUIDsKey : @[iServiceId]}];
}

- (void)peripheralManager:(CBPeripheralManager *)iPeripheral didReceiveWriteRequests:(NSArray *)iRequests {
    CBATTRequest *aRequest = iRequests[0];
    NSData *aData = aRequest.value;
    NSDictionary *aResponse = (NSDictionary *)[NSJSONSerialization JSONObjectWithData:aData options:NSJSONReadingMutableContainers error:nil];

    NSLog(@"Received Data = %@",aResponse);
}

解决方法

我已经弄清楚了.问题在于特征类型.而不是“CBCharacteristicWriteWithResponse”我使用了“CBCharacteristicWriteWithoutResponse”并且它起作用了.

我读完之后就这样做了：

writeValue forCharacteristic writeType,此函数是写入设备特性的主要函数. writeType属性设置为write而没有响应或写入响应.当使用带有响应的写入时,在iOS设备等待接收ok响应和回调时,将缓存对外围设备的所有写入.写入时不使用响应,不会缓存数据.这对于使用需要低延迟的东西很重要,比如RC汽车或直升机等.当使用带响应的写入时,iOS设备可能有时会落后,这不会产生很好的响应……对于每次写入,都会调用didWriteCharacteristic回调.