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SCharacteristic data always nil


8 posts


I can't tell you how excited I am to be playing with a slot car API. My Swift app is able to connect to the periphial and see all of the services and their characteristics. There seems to be an issue with the way I am getting data from the characteristics. No matter which I check or what I do, the characteristic data is always nil. For starters I am looking for the device data. Is there a Swift example of retrieving data from the API?



1133 posts

Hi Joe - welcome to the forum!


I am presuming you are playing with the swift app to have a look around the ARC powerbase. Maybe you are looking to write your own app to run races etc? Scalextric have released the Bluetooth communication protocols for the powerbase, which you will want to have a look at, if you haven’t already:


I’m not sure how many people that read these forums have tried to do what you are doing. Possibly a better place to post would be the Scalextric Digital section of Slot Forum.


I hope that helps. Let us know how you get on.

Andy Player


8 posts

Figured it out!

You can not read the characteristic data directly. You need to first call

peripheral.readValue(for: characteristic)

Then wait for the delegate method to be called, from within the handler the data is available. 

func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?)

Back to the races!


1133 posts

Glad you got it sorted! Do let us know how you progress with your project.


Have fun!

Andy Player

Andy P.

2061 posts

Community Moderator

This sounds all very interesting.

Please keep it up!


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