how to insert images in collection view cell

I want to insert three images in collection view cell, 3 images. One image for each cell.Only one section. But when the simulator shows black screen, no any images. Here is part of my code:

import Foundation
import UIKit

class CatImagesViewController:UIViewController,UICollectionViewDataSource,UICollectionViewDelegate
{
func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    return 1
}
func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    return 3
}

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

    let con = CatService(test:"test")

    let temp = NSUserDefaults()
    let  number = temp.integerForKey("num_of_images")

    var title_array:Array<String> = con.imageNamesForCategoryAtIndex(number)

    var string:String = title_array[indexPath.row]

    print("indexPath.row \(indexPath.row)");
    print("string is \(string)")

    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("firstCollectionCell", forIndexPath: indexPath)

    let imageview:UIImageView=UIImageView(frame: CGRectMake(50, 50, self.view.frame.width-200, 50))
    let image:UIImage = UIImage(named:string)!
    imageview.image = image
   // self.view.addSubview(imageview)
    cell.contentView.addSubview(imageview)
    return cell
}
}

I revised cell.contentView.addSubview(image view), but still black screen.

Solution

You should use

cell.contentView.addSubview(imageview)

indexPath.row is used to know the cell position in the table.

To set the height:

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
    return CGSizeMake(50, 414)
}

And you should use the property item of NSIndexPath

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

let con = CatService(test:"test")

let temp = NSUserDefaults()
let  number = temp.integerForKey("num_of_images")

var title_array:Array<String> = con.imageNamesForCategoryAtIndex(number)

var string:String = title_array[indexPath.item]

print("indexPath.row \(indexPath.item)");
print("string is \(string)")

let cell = collectionView.dequeueReusableCellWithReuseIdentifier("firstCollectionCell", forIndexPath: indexPath)

let imageview:UIImageView=UIImageView(frame: CGRectMake(50, 0, self.view.frame.width-200, 50))
let image:UIImage = UIImage(named:string)!
imageview.image = image
cell.contentView.addSubview(imageview)
return cell
}