Pinch to zoom camera

Question

I\'m trying to make a pinch to zoom camera but I\'m encountering two problems. First is that it allows the user to zoom way too much in and way to much out, secondly when I take

Answer 1

    var device: AVCaptureDevice = self.backCamera
    var vZoomFactor = sender.scale
    var error:NSError!
    do{
        try device.lockForConfiguration()
        defer {device.unlockForConfiguration()}
        if (vZoomFactor <= device.activeFormat.videoMaxZoomFactor) {

            let desiredZoomFactor:CGFloat = vZoomFactor + atan2(sender.velocity, 5.0);
            device.videoZoomFactor = max(1.0, min(desiredZoomFactor, device.activeFormat.videoMaxZoomFactor));
        }
        else {

            NSLog("Unable to set videoZoom: (max %f, asked %f)", device.activeFormat.videoMaxZoomFactor, vZoomFactor);
        }
    }
    catch error as NSError{

        NSLog("Unable to set videoZoom: %@", error.localizedDescription);
    }
    catch _{

    }