Change UIImageView.image with delay

Question

Okay, so I'm trying to create a "slideshow" of sorts by creating a class that would store an array of UIImages , and have a function that would choose a random index from the array and then assign the associate image to the image view in ViewController.h

import UIKit
import AVFoundation

class ViewController: UIViewController {


var audioPlayer = AVAudioPlayer()
var audioPath = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("1-08 Patient Love", ofType: "mp3")!)
var playPauseBtn = UIBarButtonItem()
var musicPaused: Bool = false

@IBOutlet var toolbar: UIToolbar!  
@IBOutlet var bg1: UIImageView!
@IBOutlet var bg2: UIImageView!
@IBOutlet var bg3: UIImageView!
@IBOutlet var bg4: UIImageView!
@IBOutlet var bg5: UIImageView!
@IBOutlet var bg6: UIImageView!
@IBOutlet var bg7: UIImageView!
@IBOutlet var bg8: UIImageView!
@IBOutlet var bg9: UIImageView!
@IBOutlet var bg10: UIImageView!
@IBOutlet var bg11: UIImageView!

override func viewDidLoad() {
    super.viewDidLoad()

    do{
        audioPlayer = try AVAudioPlayer(contentsOfURL: audioPath)}
    catch {
            print("Audio file not found.")
        }
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBAction func playPause(sender: UIBarButtonItem){

    var items = toolbar.items!

    if musicPaused == false {

        playPauseBtn = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Pause, target: self, action: "playPause:")

        items[0] = playPauseBtn

        toolbar.setItems(items, animated: true)

        audioPlayer.play()
        musicPaused = true

    }else{

        var items = toolbar.items!

        playPauseBtn = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Play, target: self, action: "playPause:")
        items [0] = playPauseBtn
        toolbar.setItems(items, animated: true)

        audioPlayer.pause()
        musicPaused = false
    }
}

@IBAction func stopButton(sender: AnyObject) {

    var items = toolbar.items!
    audioPlayer.stop()
    audioPlayer.currentTime = 0
    playPauseBtn = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Play, target: self, action: "playPause:")
    items[0] = playPauseBtn
    toolbar.setItems(items, animated: true)
    musicPaused = false
}
}

This is my view controller.swift file. I don't have a reference yet to the function I'm trying to write in a slideshow.swift file here

import UIKit

var imageArray: [UIImage] = [
UIImage(named: "dec11.jpg")!,
UIImage(named: "dec18.jpg")!,
UIImage(named: "dec19.jpg")!,
UIImage(named: "dec19-2.jpg")!,
UIImage(named: "dec24.jpg")!,
UIImage(named: "dec25.jpg")!,
UIImage(named: "dec30.jpg")!,
UIImage(named: "jan1.jpg")!,
UIImage(named: "jan20.jpg")!,
UIImage(named: "jan24.jpg")!,
UIImage(named: "jan30.jpg")!
]

The slideshow class is

class slideshow: NSObject {

func changeImage() -> UIImage{
    //wait 2 secs
    let seconds = 2.0
    let delay = seconds * Double(NSEC_PER_SEC)  // nanoseconds per seconds
    let dispatchTime = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))

    dispatch_after(dispatchTime, dispatch_get_main_queue(), {

        //here code perfomed with delay
        //generate random number
        let randomIndex = Int(arc4random_uniform(11))

        var imageAtIndex = imageArray[randomIndex]

        return imageAtIndex
    })
}
}

Would it be easier to just write this all in view controller? I changed the function declaration as per the suggestion of other users, but I'm still getting the same error.

Answer 1

You can't have two declarations of the variable image . You have one that is passed into the function:

@IBAction func changeImage (image: UIImage){

And another that is part of your delayed action:

    //return image at index
    var image = imageAtIndex

You don't want to return the image, you want to set the image property of the UIImageView to the image from the array, assuming your array contains UIImage .

So change your function decalaration to be

func changeImage (imageViewToChange: UIImageView){

Then change the dispatch_after code to be

dispatch_after(dispatchTime, dispatch_get_main_queue(), {

    //here code performed after delay
    //generate random number
    let randomIndex = Int(arc4random_uniform(11))

    //return image at index
    imageViewToChange.image = imageArray[randomIndex]
})

Answer 2

The following code is untested but you should be able to do something like the following. The slideshow class contains the list of possible images with a start and stop method. The animate method calls recursively so you don't have to call it from your vc every time.

import UIKit
import AVFoundation

class ViewController: UIViewController {

var audioPlayer = AVAudioPlayer()
var audioPath = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("1-08 Patient Love", ofType: "mp3")!)
var playPauseBtn = UIBarButtonItem()
var musicPaused: Bool = false

@IBOutlet var toolbar: UIToolbar!  
@IBOutlet var bg: UIImageView!

override func viewDidLoad() {
    super.viewDidLoad()

    do{
        audioPlayer = try AVAudioPlayer(contentsOfURL: audioPath)}
    catch {
            print("Audio file not found.")
        }
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBAction func playPause(sender: UIBarButtonItem){

    var items = toolbar.items!

    if musicPaused == false {

        playPauseBtn = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Pause, target: self, action: "playPause:")

        items[0] = playPauseBtn

        toolbar.setItems(items, animated: true)

        audioPlayer.play()
        musicPaused = true
        slideshow.startSlideshow(bg)

    }else{

        var items = toolbar.items!

        playPauseBtn = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Play, target: self, action: "playPause:")
        items [0] = playPauseBtn
        toolbar.setItems(items, animated: true)

        audioPlayer.pause()
        slideshow.stopSlideshow()
        musicPaused = false
    }
}

@IBAction func stopButton(sender: AnyObject) {

    var items = toolbar.items!
    audioPlayer.stop()
    audioPlayer.currentTime = 0
    playPauseBtn = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Play, target: self, action: "playPause:")
    items[0] = playPauseBtn
    toolbar.setItems(items, animated: true)
    musicPaused = false
    slideshow.stopSlideshow()
}
}


class slideshow: NSObject {

var imageArray: [UIImage] = [
UIImage(named: "dec11.jpg")!,
UIImage(named: "dec18.jpg")!,
UIImage(named: "dec19.jpg")!,
UIImage(named: "dec19-2.jpg")!,
UIImage(named: "dec24.jpg")!,
UIImage(named: "dec25.jpg")!,
UIImage(named: "dec30.jpg")!,
UIImage(named: "jan1.jpg")!,
UIImage(named: "jan20.jpg")!,
UIImage(named: "jan24.jpg")!,
UIImage(named: "jan30.jpg")!
]
var shouldAnimate: boolean?

func startSlideshow(imageView: UIImageView) {
    shouldAnimate = true
    self.animate()
}

func stopSlideshow() {
    shouldAnimate = false
}

func animate() {
        //wait 2 secs
    let seconds = 2.0
    let delay = seconds * Double(NSEC_PER_SEC)  // nanoseconds per seconds
    let dispatchTime = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))

    dispatch_after(dispatchTime, dispatch_get_main_queue(), {

        //here code perfomed with delay
        //generate random number
        let randomIndex = Int(arc4random_uniform(11))

        var imageAtIndex = imageArray[randomIndex]

        imageView.image = imageAtIndex
        if (shouldAnimate) {
          self.animate()
        }
    })
  }
}