Cannot convert value of type (CMAccelerometerData!, NSError!) in
<p>It keeps saying Cannot convert value of type <code>(CMAccelerometerData!, NSError!)</code> . How can I change it?</p>

<pre><code>motionManager.startAccelerometerUpdatesToQueue(NSOperationQueue.currentQueue()!, withHandler: {
            (accelerometerData: CMAccelerometerData!, error: NSError!) in
            // 3
            let acceleration = accelerometerData.acceleration
            // 4
            self.xAcceleration = (CGFloat(acceleration.x) * 0.75) + (self.xAcceleration * 0.25)
            })
</code></pre>