保存收藏按钮状态

Question

我正在尝试通过保存状态来完成我最喜欢的按钮，即使我退出视图 \App 也是如此。如果有人能告诉我如何做到这一点，那就太好了，我正在使用 Xcode 8 并使用 Swift 3 进行编码。

当前按钮代码：

 //create a new button
        let Favoritebutton: UIButton = UIButton(type: UIButtonType.custom)
        //set image for button
        Favoritebutton.setImage(UIImage(named: "EmptyHeart.png"), for: .normal)
        Favoritebutton.setImage(UIImage(named: "FilledHeart.png"), for: .selected)
        //add function for button
        Favoritebutton.addTarget(self, action: #selector(self.button), for: .touchUpInside)
        //set frame
        Favoritebutton.frame = CGRect(x:0,y: 0,width: 35,height: 35)
        
        let barButton = UIBarButtonItem(customView: Favoritebutton)
        //assign button to navigationbar
        
        self.navigationItem.rightBarButtonItem = barButton
        
        let state = UserDefaults.standard.bool(forKey: "isSaved") ?? false
        
        }


    @IBAction func button(sender: UIButton) {
        
        sender.isSelected = !sender.isSelected
        
        UserDefaults.standard.set(true,forKey: "isSaved")
        UserDefaults.standard.synchronize()
        
        
        
        if let Favoritebutton = sender as? UIButton {
            if Favoritebutton.isSelected {
                // set selected
                Favoritebutton.isSelected = true
                UserDefaults.standard.set(true, forKey: "MY_FAV_KEY")
                UserDefaults.standard.synchronize()
                
                
                
                  // set badge to tabbar item.
        let tabItem = self.tabBarController?.tabBar.items![3]
        sel_val = tabItem?.badgeValue
        if(sel_val == nil){
            sel_val = "0"
        }
        let sel_num  = Int(sel_val!)
        tabItem!.badgeValue = String(format: "%d", sel_num! + 1) as String
        
        let Fav: NSMutableArray = []
        Fav.add(barImage)
        Fav.add(barName)
        Fav.add(streetName)
        favorite.add(Fav)
        

                
                
            } else {
                // set deselected
                Favoritebutton.isSelected = false
                UserDefaults.standard.set(true, forKey: "MY_FAV_KEY")
                UserDefaults.standard.synchronize()
            
                
                let tabItem = self.tabBarController?.tabBar.items![3]
                sel_val = tabItem?.badgeValue
                if(sel_val == nil){
                    sel_val = "0"
                }
                let sel_num  = Int(sel_val!)
                tabItem!.badgeValue = String(format: "%d", sel_num! - 1) as String
                let Fav: NSMutableArray = []
                Fav.add(barImage)
                Fav.add(barName)
                Fav.add(streetName)
                favorite.remove(Fav)
                
                
            }
        }
        

正如我所说，如果有人能帮我保存按钮的状态，那就太好了 即使我退出视图或应用程序，我也会非常感激，提前谢谢！

Answer 1

将值保存到 UserDefaults 会将其写入 plist 文件。当应用程序恢复时，它不会读回值或恢复状态。你对此负责。所以在 viewDidLoad 某处检查状态：

let state = UserDefaults.standard.bool(forKey: "isSaved") ?? false

然后相应地设置您的按钮