"Sending uncached message without first clearing the previously cached value" How can I fix this?

Question

So I declared a timer:

self.timer = Timer.scheduledTimer(timeInterval: 0.01, target: self, selector: #selector(self.updateWatch), userInfo: data!, repeats: true)

(data is of type CMMotionActivity)

Then I get the userInfo in my updateWatch() function:

let data = timer.userInfo as! CMMotionActivity

But when trying it the program fails with "[Client] #Warning Sending an un-cached message 'kCLConnectionMessageMotionActivityUpdate' without first clearing the previously cached value"

How can I solve this?