我尝试从BLE设备读取数据，但不断获得权限错误。演示项目可以在这里找到：https://github.com/sergiomtzlosa/CoreBluetooth-Demo（请记住-我的代码和这个有点不同）。
连接和读取值一般没有问题，但有一些特征（这是必不可少的）给出了许可错误。
控制台日志：* 更新错误！！！特性：“Unknown（< fff4 >）”出现错误：“不允许读取”。*
因此，当我订阅或读取该特性的数据时，它每次都向我发送NULL（可能的原因：没有读取许可）。
控制台日志：* 特点：“未知（< fff4 >）”-〉值为：（空值）*
下面是一个代码段：

//Action on discovering services
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error
{

if (error) 
{
    NSLog(@"Discovered services for %@ with error: %@", peripheral.name, [error localizedDescription]);
    return;
}
for (CBService *service in peripheral.services) {

    NSLog(@"Discovereddddddddddd service %@", service.UUID);
    [testPeripheral discoverCharacteristics:nil  forService:service];
}
 NSLog(@"didDiscoverServicesEnd");
}

//Action on discovered characteristics
- (void)peripheral:(CBPeripheral *)peripheral
didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error {
NSLog(@"didDiscoverCharacteristicsForService!");
for (CBCharacteristic *characteristic in service.characteristics) {
    NSLog(@"Discovered characteristic %@", characteristic.UUID);
    NSLog(@"---------------------------------------------------");
    NSLog(@"Reading value for characteristic %@", characteristic.UUID);
    [peripheral readValueForCharacteristic:characteristic];
    NSLog(@"+++++++++++++++++++++++++++++++++++++++++++++++++++");
    [peripheral setNotifyValue:YES forCharacteristic:characteristic];
    }
}

//Action on reading value
- (void)peripheral:(CBPeripheral *)peripheral 
didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{
if (error){
    NSLog(@"Update error!!! Characteristic: %@ with error: %@", characteristic.UUID, [error localizedDescription]);
    return;
}else{
    NSData *data = characteristic.value;
    NSString *str = [NSString stringWithUTF8String:[data bytes]];
    NSLog(@"Characteristic: %@ -> with value: %@", characteristic.UUID, str);
}
}

怎么了？有办法克服这个问题吗？