Central.m

- (void)peripheral:(CBPeripheral *)peripheral
didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic
             error:(NSError *)error {
    if (error) {
        return;
    }

    if (characteristic.value == nil) {
        return;
    }

    NSString *value = [[NSString alloc] initWithData:characteristic.value encoding:NSUTF8StringEncoding];
    if ([_delegate respondsToSelector:@selector(BLECentralComponentReceiveMessage:message:)]) {
        __weak typeof(self) weakSelf = self;
        dispatch_async(dispatch_get_main_queue(), ^{
            [weakSelf.delegate BLECentralComponentReceiveMessage:self message:value];
        });
    }
}