不小心改了一个地方结果一直报一个错Error Domain=CBErrorDomain Code=0，
后来和之前的对比了一下，发现是UUID导致的错误
看红色部分，是由于改变了UUID导致的
2015-05-28 17:05:32.034 bluetoothDemo[704:71315] didWriteValueForCharacteristic <CBCharacteristic: 0x146aa0f0, UUID = FFF2, properties = 0x8, value = (null), notifying = NO> error = (null) // 没有报错的时候
2015-05-28 17:07:05.700 bluetoothDemo[704:71315] didWriteValueForCharacteristic <CBCharacteristic: 0x1466e070, UUID = FFF1, properties = 0x10, value = <20010203 04050607>, notifying = YES> error = Error Domain=CBErrorDomain Code=0 "Unknown error." UserInfo=0x146ad520 {NSLocalizedDescription=Unknown error.} //报错的时候