UICollectionView Horizontal Scroll

I try to do a UICollectionView that print 1,5 cell on screen, and with the scroll you should be able to display the next cells. But here is the problem, I arrive to display 1,5 cell but I can't scroll. I don't know why, when I set the layout "scrollDirection" property to "Horizontal" that create a Vertical scroll.

Here is the layout and UICollectionView initialization:

let screenSize = UIScreen.mainScreen().bounds
let widthImage = (screenSize.width - CGFloat(8)) / 1.5
let heightImage = UIUtils.getHeightAspectRatio(widthImage)
//let sizeCollectionView: CGSize = CGSize(width: widthImage, height: heightImage)
let layout = UICollectionViewFlowLayout()
layout.itemSize = CGSize(width: widthImage, height: heightImage)
howTo = UICollectionView(frame: self.view.bounds, collectionViewLayout: layout)
howTo!.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: "howToCell")
howTo!.tag = 0
howTo!.delegate = self
howTo!.dataSource = self
self.view.addSubview(howTo!)
howTo!.snp_makeConstraints { (make) -> Void in make.top.equalTo(readMoreText.snp_bottom).offset(5) make.leading.equalTo(self.view).offset(5) make.trailing.equalTo(self.view) make.height.equalTo(115)
}
howTo?.backgroundColor = UIColor.whiteColor()
howTo?.contentMode = .ScaleToFill
howTo?.scrollEnabled = true

And here is the method called when you display the cell:

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
if collectionView.tag == howTo!.tag { let cell = collectionView.dequeueReusableCellWithReuseIdentifier("howToCell", forIndexPath: indexPath) if let url = NSURL(string:UIUtils.getImageUrl(self.exercise.getHowTos()[indexPath.row].getImages(), label: Image.mediumWide)) { let screenSize = UIScreen.mainScreen().bounds let widthImage = (screenSize.width - CGFloat(8)) / 1.5 let heightImage = UIUtils.getHeightAspectRatio(widthImage) let img = UIImageView(frame: CGRect(x: 0, y: 0, width: widthImage, height: heightImage)) img.af_setImageWithURL(url) cell.contentView.addSubview(img) cell.backgroundView = cell.contentView } else { let img = UIImageView(frame: cell.frame) img.image = R.image.appIconTemp() cell.contentView.addSubview(img) cell.backgroundView = cell.contentView //cell.backgroundColor = UIColor.blackColor() }

If you have any idea why I can't scroll you'll made my day !

Thanks