Translucent white covering my button in UITableView - ios

Question

I've set constraints and everything but there's a translucent white "screen" covering the lower part of my screen. It's not fixed to my tableview because when I scroll down the button gets pulled up and is visible but the screen stays there. At first I thought it was a rogue view but it's not so I'm not sure what's going on. Any pointers on what I should be looking at to solve this problem? Here's a picture:
Here is my code (a little untidy because this is my first project in swift):
import UIKit
class MainViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var buttonView: UIView!
#IBOutlet weak var button: UIButton!
#IBOutlet weak var tableView: UITableView!
let manager = WorkoutDataSource()
let gradientLayer = CAGradientLayer()
var workouts = []
override func viewDidLoad() {
super.viewDidLoad()
self.tableView.delegate = self
self.tableView.dataSource = self
self.workouts = manager.getWorkOuts()
let borderAlpha : CGFloat = 0.7
let cornerRadius : CGFloat = 5.0
button.backgroundColor = UIColor.clearColor()
button.layer.borderWidth = 1.0
button.layer.borderColor = UIColor(white: 1.0, alpha: borderAlpha).CGColor
button.layer.cornerRadius = cornerRadius
let heightOfVisibleTableViewArea = tableView.bounds.height - topLayoutGuide.length - bottomLayoutGuide.length
let numberOfRows = tableView.numberOfRowsInSection(0)
tableView.rowHeight = heightOfVisibleTableViewArea / CGFloat(numberOfRows)
let color1 = UIColor(hue: 0.9528, saturation: 0.4, brightness: 1, alpha: 1.0) /* #ff759d */
let color2 = UIColor(hue: 0.0167, saturation: 0.25, brightness: 0.95, alpha: 1.0) /* #ffb1b1 */
let color3 = UIColor(hue: 0.2528, saturation: 0.11, brightness: 0.85, alpha: 1.0) /* #f3bbb4 */
let color4 = UIColor(hue: 0.3833, saturation: 0.21, brightness: 0.91, alpha: 1.0) /* #cedbc2 */
let color5 = UIColor(hue: 0.4417, saturation: 0.62, brightness: 0.97, alpha: 1.0) /* #b7eac7 */
let color6 = UIColor(hue: 0.4528, saturation: 0.91, brightness: 0.81, alpha: 1.0) /* #12d19e */ /* #5ef9c3 */
//let color7 = UIColor(hue: 0.5833, saturation: 0.7, brightness: 0.68, alpha: 1.0) /* #346fae */
let color7 = UIColor.flatNavyBlueColorDark()
gradientLayer.colors = [color1, color2, color3, color4, color5, color6, color7]
view.backgroundColor = UIColor.flatNavyBlueColorDark()
setTableViewBackgroundGradient(color7, bottomColor: color1)
self.navigationController?.navigationBar.backgroundColor = UIColor.flatNavyBlueColorDark()!
// Do any additional setup after loading the view, typically from a nib.
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int{
return self.workouts.count
}
func setTableViewBackgroundGradient(topColor: UIColor, bottomColor: UIColor){
let gradientBackgroundColors = [topColor.CGColor, bottomColor.CGColor]
let gradientLocations = [0.0,1.0]
let gradientLayer = CAGradientLayer()
gradientLayer.colors = gradientBackgroundColors
gradientLayer.locations = gradientLocations
gradientLayer.frame = tableView.bounds
let backgroundView = UIView(frame: tableView.bounds)
backgroundView.layer.insertSublayer(gradientLayer, atIndex: 0)
tableView.backgroundView = backgroundView
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell{
let workout = self.workouts[indexPath.row] as? Workout
let cell = tableView.dequeueReusableCellWithIdentifier("Cell") as? WorkoutCell
cell!.textCellLabel?.text = workout?.title
cell!.backgroundColor = workout?.color
cell!.countLabel.text = "\(indexPath.row+1)"
cell!.selectionStyle = UITableViewCellSelectionStyle.None
cell!.backgroundColor = UIColor.clearColor()
return cell!
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "detailview"){
let cell = sender as? WorkoutCell
let indexPath = tableView.indexPathForCell(cell!)
let nvc = segue.destinationViewController as? UINavigationController
if let tmp = workouts[indexPath!.row] as? Workout{
let dvc = nvc?.topViewController as! DetailViewController
dvc.workout = tmp
}
}
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
self.tableView.contentInset = UIEdgeInsetsMake(0,0,55,0)
}
}