Swift中关联随机图片生成器与第二个视图控制器及崩溃修复

1. 修复数组越界崩溃，实现图片耗尽时跳转 #

修改主ViewController的randomButtonPressed方法，先检查当前索引是否在数组范围内，超出时执行页面跳转：

@IBAction func randomButtonPressed(_ sender: UIButton) {
    // 检查是否还有未显示的图片
    guard imageMain < array.count else {
        // 图片耗尽，跳转到重置页面
        performSegue(withIdentifier: "goToResetVC", sender: self)
        return
    }
    
    mainImageView.image = array[imageMain]
    imageMain += 1
}

注意：需要在Storyboard中给主VC到第二个VC的segue设置标识符为goToResetVC；如果用代码跳转，可替换为present(ResetViewController(), animated: true)。

2. 配置重置页面（ResetViewController） #

在已创建的第二个ViewController中，给重置按钮添加点击事件，实现返回主页面的逻辑：

import UIKit

class ResetViewController: UIViewController {
    @IBAction func resetButtonPressed(_ sender: UIButton) {
        // 关闭当前页面回到主VC
        dismiss(animated: true)
    }
}

3. 主VC返回后重置状态并重新洗牌 #

在主ViewController中重写viewWillAppear方法，每次回到主页面时自动重置索引、洗牌数组并恢复初始图片：

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    // 重新洗牌图片数组
    array.shuffle()
    // 重置图片索引
    imageMain = 0
    // 恢复初始显示图片
    mainImageView.image = #imageLiteral(resourceName: "start-image")
}

完整修改后的主VC代码 #

import UIKit

class ViewController: UIViewController {
    
    @IBOutlet weak var mainImageView: UIImageView!
    
    var imageMain = 0
    var array = [ #imageLiteral(resourceName: "raven-988218_1280"), #imageLiteral(resourceName: "halloween-2905531_1280"), #imageLiteral(resourceName: "bird-skull-4433244_1280"), #imageLiteral(resourceName: "candles-1868640_1280"), #imageLiteral(resourceName: "tombstone-2542946_1280"), #imageLiteral(resourceName: "fantasy-2847724_1280") ]
    
    override func viewDidLoad() {
        super.viewDidLoad()
        mainImageView.image = #imageLiteral(resourceName: "start-image")
        array.shuffle()        
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        array.shuffle()
        imageMain = 0
        mainImageView.image = #imageLiteral(resourceName: "start-image")
    }
    
    @IBAction func randomButtonPressed(_ sender: UIButton) {
        guard imageMain < array.count else {
            performSegue(withIdentifier: "goToResetVC", sender: self)
            return
        }
        
        mainImageView.image = array[imageMain]
        imageMain += 1
    }
}

内容的提问来源于stack exchange，提问作者TheOtisLegion