快速for循环与睡眠

我有一个 Swift 4 ios 应用程序，按下按钮时会显示随机消息和照片。这工作正常，但我想创建一个无限循环来在按下按钮时显示随机消息/照片。我尝试了多种方法来实现这一目标，但没有一个有效。在主线程完成之前，标签和图像视图似乎不会更新。下面是我目前尝试的方法，这甚至不是无限循环，但仍然存在相同的问题。打印语句显示在调试窗口中，但标签和图像视图从未更新。

@IBAction func loveButtonPressed(_ sender: UIButton) {

    nextNote()

}


func nextNote() {

    for number in 1...1000 {

        print("number is \(number)")
        randomPhoto = Int(arc4random_uniform(18))

        if randomPhoto == lastRandomPhoto {
            randomPhoto = Int(arc4random_uniform(18))
        }

        photoDisplay.image = UIImage(named: photoArray[randomPhoto])

        lastRandomPhoto = randomPhoto

        randomNum = Int(arc4random_uniform(14))

        if randomNum == lastRandomNum {
            randomNum = Int(arc4random_uniform(14))
        }

        loveNote.text = msgArray[randomNum]
        lastRandomNum = randomNum
        print("end of loop before sleep")
        sleep(6)
        print("end of sleep")
    }
}

你可以使用Timer反而...

var timer: Timer!

func nextNote() {
    self.timer = Timer.scheduledTimer(timeInterval: 6.0, target: self, selector: #selector(self.setPhoto), userInfo: nil, repeats: true)
}

@objc func setPhoto() {

    randomPhoto = Int(arc4random_uniform(18))

    if randomPhoto == lastRandomPhoto {
        randomPhoto = Int(arc4random_uniform(18))
    }

    photoDisplay.image = UIImage(named: photoArray[randomPhoto])

    lastRandomPhoto = randomPhoto

    randomNum = Int(arc4random_uniform(14))

    if randomNum == lastRandomNum {
        randomNum = Int(arc4random_uniform(14))
    }

    loveNote.text = msgArray[randomNum]
    lastRandomNum = randomNum
}

func somethingToEndTheLoop() {
    self.timer.invalidate()
}