Toggle image when the user touch the image - ios

Question

I'm trying to do two things in Swift:
· When the user touches the image, toggle between the filtered, and original images temporarily.
· When the user lifts their finger, toggle back.
But I don't know what functions or modules to use, any suggestions?
I have got a image View and four buttons 「New Photo」,「Filter」,「Compare」,「Share」.

Answer 1

Try this
override func viewDidLoad(){
super.viewDidLoad()
// add Tap gesture recognizer to ImageView
let imageView = self.your_imageView
let tapGestureRecognizer = UILongPressGestureRecognizer(target:self, action:Selector("toggleImage:"))
imageView.userInteractionEnabled = true
imageView.addGestureRecognizer(tapGestureRecognizer)
}
func toggleImage(sender: UILongPressGestureRecognizer){
if sender.state == .Began{
originalImage()
}else if sender.state == .Ended{
filteredImage()
}
}
It uses UILongPressGestureRecognizer()

Answer 2

I would recommend looking into UILongPressGestureRecognizer.
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UILongPressGestureRecognizer_Class/index.html#//apple_ref/occ/instp/UILongPressGestureRecognizer/minimumPressDuration
When the gesture begins, change the UIImage being displayed. You can detect when the gesture ends with UIGestureRecognizerStateEnded. I'm sure you'll figure it out!

Answer 3

I set the minimum press duration to 0.1 from default 0.5 to make it look like a tap button. Code changes to check if the filtered image is not nil and it is not equal to the original image. I set back and forth the image view according the state began and end
override func viewDidLoad() {
super.viewDidLoad()
// adding Tap gesture recognizer to image view
let longPressGestureRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(imageTapped(_:)))
// Enabling the user interaction for the image view
imageView.userInteractionEnabled = true
imageView.addGestureRecognizer(longPressGestureRecognizer)
// Changing the default minimum press duration from 0.5 to 0.1
longPressGestureRecognizer.minimumPressDuration = 0.1
}
// image tapped function that changes the image view when the user presses on the image view
func imageTapped(longPressGestureRecognizer: UILongPressGestureRecognizer) {
if longPressGestureRecognizer.state == .Began {
imageView.image = originalImage
} else if longPressGestureRecognizer.state == .Ended {
if filteredImage != nil && filteredImage != originalImage {
imageView.image = filteredImage
}
}
}