Swift 3 - 重新加載NavigationController按鈕圖像

Question

我有一個導航控制器視圖，帶有嵌入式collectionview控制器。我有加入編程右欄按鈕，與圖像添加到它如下：

self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: #imageLiteral(resourceName: "greyCircle").withRenderingMode(.alwaysOriginal), style: .plain, target: self, action: #selector (handleGrayCircleButton)) 

我想，關於這個按鈕點擊一個用戶，才能夠將圖像從灰更改爲銀。我有按鈕處理程序設置成從灰度切換到銀與每個壓榨：

 self.navigationItem.rightBarButtonItem?.image = UIImage(named: "greyCircle") 

然而，圖像僅切換回之前改變簡要介紹。我試圖將圖像的顏色保存爲「標誌」變量，即，如果它當前是灰色的，則轉爲銀色，以便使更改保持不變，但是，圖像會不斷重置爲任何加載的圖像（或者與viewDidLoad或viewWillAppear）。

無論如何刷新/重新載入導航控制器標籤欄後，每次點擊並使其持續，連同圖像的酒吧按鈕？

＃

編輯：以下是完整的按鈕處理程序。

func handleFavoritePress(){ 
     print("Favorites pressed") 
     if(!returnTrueIfInFavorites(objectName: readString(object: self.patientRecord!, key: "name"), objectType: LIST_CoreDataBaseObjects.Patients)){ 
      // Add to favorites 
      Favorites_Names.append(readString(object: self.patientRecord!, key: "name")) 
      Favorites_Types.append(LIST_CoreDataBaseObjects.Patients) 


      // Let user know 
      let patientName = readString(object: self.patientRecord!, key: "name") 
      let alertController = UIAlertController(title: "Alert!", message: "\(patientName) has been added to your favorites.", preferredStyle: .alert) 
      let defaultAction = UIAlertAction(title: "OK", style: .default, handler: nil) 
      alertController.addAction(defaultAction) 
      var rootViewController = UIApplication.shared.keyWindow?.rootViewController 
      if let navigationController = rootViewController as? UINavigationController { 
       rootViewController = navigationController.viewControllers.first 
      } 
      if let tabBarController = rootViewController as? UITabBarController { 
       rootViewController = tabBarController.selectedViewController 
      } 
      rootViewController?.present(alertController, animated: true, completion: nil) 
      self.navigationItem.rightBarButtonItem?.image = UIImage(named: "savedFavorite_1") 

     }else{ 

      self.navigationItem.rightBarButtonItem?.image = UIImage(named: "favorite_2") 
      deleteFromFavorites(objectName: readString(object: patientRecord!, key: "name"), objectType: LIST_CoreDataBaseObjects.Patients) 
     } 
     for favorite in Favorites_Names{ 
      print("Favorites are currently: \(patient)") 
     } 

    } 

等功能：

override func viewWillAppear(_ animated: Bool) { 

     collectionView?.backgroundView = setBackgroundImage(imageName: "whiteBackground") 
     navigationItem.title = "Patient" 
     if(returnTrueIfInFavorites(objectName: readString(object: patientRecord!, key: "name"), objectType: LIST_CoreDataBaseObjects.Patients)){ 
      setupNavBarButtonsIsFavorited() 
     }else{ 
      setupNavBarButtonsNotFavorited() 
     } 
    } 

    func setupNavBarButtonsNotFavorited(){ 
     self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: #imageLiteral(resourceName: "favorite_2").withRenderingMode(.alwaysOriginal), style: .plain, target: self, action: #selector (handleFavoritePress)) 
    } 
    func setupNavBarButtonsIsFavorited(){ 
     self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: #imageLiteral(resourceName: "savedFavorite_1").withRenderingMode(.alwaysOriginal), style: .plain, target: self, action: #selector (handleFavoritePress)) 
    } 

Answer 1

的回答你的問題就在於內這兩LIST_CoreDataBaseObjects.Patients，returnTrueIfInFavorites或patientRecord變量。

要麼LIST_CoreDataBaseObjects.Patients未更新你的函數handleFavoritePress的代碼

/* this code */ 
Favorites_Names.append(readString(object: self.patientRecord!, key: "name")) 
Favorites_Types.append(LIST_CoreDataBaseObjects.Patients) 
/* this code */ 

因爲從你在評論部分已經解釋什麼，如果我理解正確的話，就是當你自來水的按鈕圖像發生變化，然後導航到不同的視圖，但當您回到導航時，將觸發viewDidAppear(_:)和viewWillAppear(_:)。

哪個代碼塊下面我將解釋

// this function will be triggered everytime you navigate into this view (because it has appeared) 
override func viewWillAppear(_ animated: Bool) { 
    /* don't forget to call super.viewWillAppear(true) */ 
    super.viewWillAppear(true) 
    /* don't forget to call super.viewWillAppear(true) */ 

    collectionView?.backgroundView = setBackgroundImage(imageName: "whiteBackground") 

    navigationItem.title = "Patient" 

    // the problem lies here 
    /* the function `(returnTrueIfInFavorites(objectName: readString(object: patientRecord!, key: "name"), objectType: LIST_CoreDataBaseObjects.Patients))` is always returning one thing which is why your image returns back to its previous state */ 
    if (returnTrueIfInFavorites(objectName: readString(object: patientRecord!, key: "name"), objectType: LIST_CoreDataBaseObjects.Patients)) { 
     setupNavBarButtonsIsFavorited() // only one of these gets called 
    } else { 
     setupNavBarButtonsNotFavorited() // only one of these gets called 
    } 
} 

func setupNavBarButtonsNotFavorited() { 
    self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: #imageLiteral(resourceName: "favorite_2").withRenderingMode(.alwaysOriginal), style: .plain, target: self, action: #selector (handleFavoritePress)) 
} 

func setupNavBarButtonsIsFavorited() { 
    self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: #imageLiteral(resourceName: "savedFavorite_1").withRenderingMode(.alwaysOriginal), style: .plain, target: self, action: #selector (handleFavoritePress)) 
} 

所有這些，或者你只是沒有更新變量self.patientRecord!的價值（我還沒有看到你的代碼與本任何設置變量）