Add UIImage to back View - arrays

Question

Video
Hey :) Im kind of new to Stack and not sure if i should have edited this instead of adding a whole new question but i figured out a way to make it more clear. So in my code i want my textImages to only show up on the front of the UIimageViews, and the "back" image to show up on only the back side of my ImageView when flipped. Right now both Images are showing up on both parts. Is there a way to addSubview() to only the back of the ImagView :/ I do not want to use UItablevView if possible. Also in the video the last looped UIimageView works just like i want but not the ImageViews before it.
import UIKit
import Foundation
class ViewController: UIViewController {
#IBOutlet weak var mainScrollView: UIScrollView!
#IBOutlet var open: UIBarButtonItem!
var myImageArray = [UIImage]()
var back: UIImageView!
var front: UIImageView!
var showingFront = true
override func viewDidLoad() {
super.viewDidLoad()
let singleTap = UITapGestureRecognizer(target: self, action: #selector(ViewController.tapped))
singleTap.numberOfTapsRequired = 1
mainScrollView.addGestureRecognizer(singleTap)
mainScrollView.isUserInteractionEnabled = true
mainScrollView.frame = view.frame
myImageArray = [textImg1, textImg2 ,textImg3, textImg4, textImg5]
for i in 0..<myImageArray.count {
front = UIImageView()
front.image = myImageArray[i]
front.contentMode = .scaleToFill
let yPosition = self.view.frame.height * CGFloat(i) + self.view.frame.height/2 - (self.view.frame.height / 1.1)/2
let xPosition = self.view.frame.width/2 - (self.view.frame.width / 1.1)/2
front.frame = CGRect(x: xPosition, y: yPosition, width: self.view.frame.width / 1.1, height: self.view.frame.height / 1.1)
front.layer.borderWidth = 5
mainScrollView.contentSize.height = mainScrollView.frame.height * CGFloat(i + 1)
mainScrollView.addSubview(front)
back = UIImageView(image: UIImage(named: "back.png"))
back.contentMode = .scaleToFill
back.frame = CGRect(x: xPosition, y: yPosition, width: self.view.frame.width / 1.1, height: self.view.frame.height / 1.1)
back.layer.borderWidth = 5
mainScrollView.addSubview(back)
}
}
func tapped() {
print("Hello")
if (showingFront) {
UIView.transition(from: front, to: back, duration: 1, options: UIViewAnimationOptions.transitionFlipFromRight, completion: nil)
showingFront = false
} else {
UIView.transition(from: back, to: front, duration: 1, options: UIViewAnimationOptions.transitionFlipFromLeft, completion: nil)
showingFront = true
}
}
}