Load imageView from Xcassets using Switch statement - ios

Question

I have the images for #1 #2 and #3 in the Xcassets and am trying to load the image onto a scrollview page using the code below that switches the image due to the age its on. The page is determined by the position and the switch statement is called in the viewWillLoad function. The images are not loading but sounds are working so I know the it is the image loading that is the problem. Can you help?
override func viewDidDisappear(animated: Bool) {
self.imageView.removeFromSuperview()
self.imageView.image = nil
}
override func viewWillAppear(animated: Bool) {
showImageView()
let tapGestureImage = UITapGestureRecognizer(target: self, action: Selector("handleTapGestureImage:"))
imageView.addGestureRecognizer(tapGestureImage)
imageView.userInteractionEnabled = true
}
// MARK: BWWalkthroughPage Implementation
func walkthroughDidScroll(position: CGFloat, offset: CGFloat) {
// getting the page number from the scroll position. First page loads as nil so want it to be zero.
screenPage = Int(((position / view.bounds.size.width) + 1) - 1)
}
func showImageView() {
// change imageView in bundle depending on which scrollview page you are.
switch screenPage {
case 0:
self.imageView.image = UIImage(named: "Aligator", inBundle: NSBundle.mainBundle(), compatibleWithTraitCollection: self.traitCollection)
self.view.addSubview(imageView)
case 1:
self.imageView.image = UIImage(named: "Bear", inBundle: NSBundle.mainBundle(), compatibleWithTraitCollection: self.traitCollection)
self.view.addSubview(imageView)
default:
self.imageView.image = nil
}
}

Answer 1

A few things are important for you to understand.
You do not need to add/remove the image view from the view hierarchy over and over. Simply calling imageView.image = nil will suffice.
The second thing is that you don't need to use the full method UIImage(named:inBundle:compatibleWithTraitCollection:). You should be able to simply use UIImage(named:). If you find yourself having to use the former, you may be taking bigger bites than you can handle at this stage in your career.
The third thing is that when you override a method, you must call super in 99% of the cases.
Here's an example that should work:
import UIKit
class MyViewController: UIViewController {
override fun viewDidLoad() {
super.viewDidLoad()
let gestureRecognizer = UITapGestureRecognizer(target: self, action: Selector("handleTapGestureImage:"))
imageView.addGestureRecognizer(gestureRecognizer)
imageView.userInteractionEnabled = true
}
override func viewDidDisappear(animated: Bool) {
super.viewDidDisappear(animated: animated)
self.imageView.image = nil
}
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated: animated)
showImageView()
}
func walkthroughDidScroll(position: CGFloat, offset: CGFloat) {
screenPage = Int(((position / view.bounds.size.width) + 1) - 1)
}
func showImageView() {
switch screenPage {
case 0:
imageView.image = UIImage(named: "Aligator")
case 1:
imageView.image = UIImage(named: "Bear")
default:
imageView.image = nil
}
}
}