UserDefault保存按钮状态

即使我退出视图\ App，我也试图通过保存状态来完成我最喜欢的按钮。 如果有人能告诉我我该怎么做，那将是很棒的，我正在使用Xcode 8并使用Swift 3进行编码。

//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) Favoritebutton.isSelected = UserDefaults.standard.bool(forKey: "isSaved") 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 if let Favoritebutton = sender as? UIButton { Favoritebutton.isSelected = UserDefaults.standard.bool(forKey: "isSaved") if Favoritebutton.isSelected { // set selected Favoritebutton.isSelected = true // set badge Value 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 //Add Favorite let Fav: NSMutableArray = [] Fav.add(barImage) Fav.add(barName) Fav.add(streetName) favorite.add(Fav) } else { // set deselected Favoritebutton.isSelected = false //Badge Value Count. 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 //Remove Favorite let Fav: NSMutableArray = [] Fav.add(barImage) Fav.add(barName) Fav.add(streetName) favorite.remove(Fav) } } 

Answer 1

您可以将button的代码减少到

 @IBAction func button(sender: UIButton) { sender.isSelected = !sender.isSelected UserDefaults.standard.set(sender.isSelected, forKey: "isSaved") } 

要设置状态，您必须将其读回

 let Favoritebutton = UIButton(type: UIButtonType.custom) //set image for button Favoritebutton.setImage(UIImage(named: "EmptyHeart.png"), for: .normal) Favoritebutton.setImage(UIImage(named: "FilledHeart.png"), for: .selected) Favoritebutton.isSelected = UserDefaults.standard.bool(forKey: "isSaved") ... 

编辑：

我不知道你的代码是做什么的，但是有很多冗余的代码。 IBAction可以减少到（未经测试，当然）

 @IBAction func button(sender: UIButton) { let newValue = !sender.isSelected sender.isSelected = newValue UserDefaults.standard.set(newValue, forKey: "isSaved") let tabItem = self.tabBarController?.tabBar.items![3] sel_val = tabItem?.badgeValue if(sel_val == nil){ sel_val = "0" } let sel_num = Int(sel_val!) let fav: NSMutableArray = [] fav.add(barImage) fav.add(barName) fav.add(streetName) if sender.isSelected { tabItem!.badgeValue = String(format: "%d", sel_num! + 1) favorite.add(fav) } else { tabItem!.badgeValue = String(format: "%d", sel_num! - 1) favorite.remove(fav) } } 

请用起始小写字母命名变量。

Answer 2

每次使用UserDefaults.standard.set都需要同步，添加UserDefaults.standard.synchronize() 。

要删除/删除已保存的值，请使用UserDefaults.standard.removeObject(forKey: "YOUR_KEY")

这是你的function

 @IBAction func button(sender: UIButton) { sender.isSelected = !sender.isSelected //one thing i tried , doesn't work : 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() //Add to favorites } else { // set deselected Favoritebutton.isSelected = false UserDefaults.standard.set(false, forKey: "MY_FAV_KEY") UserDefaults.standard.synchronize() //remove from Favorites } } }