ios - 延迟更改 UIImageView.image

Question

好的，所以我正在尝试通过创建一个类来创建各种“幻灯片”，该类将存储 UIImages 数组，并具有一个从数组中选择随机索引的函数然后将关联图像分配给ViewController.h

中的 ImageView

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
}
}

这是我的 View controller.swift 文件。我还没有对我试图在此处的 Slideshow.swift 文件中编写的函数的引用

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")!
]

幻灯片类是

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
    })
}
}

将这些全部写在 View Controller 中会更容易吗？我根据其他用户的建议更改了函数声明，但仍然遇到相同的错误。

Answer 1

变量 image 不能有两个声明。你有一个传递给函数的:

@IBAction func changeImage (image: UIImage){

还有一个是你延迟行动的一部分:

    //return image at index
    var image = imageAtIndex

您不想返回图像，而是想将 UIImageView 的图像属性设置为数组中的图像，假设您的数组包含 UIImage。

所以把你的函数声明改成

func changeImage (imageViewToChange: UIImageView){

然后将dispatch_after代码改为

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]
})