我有一个导航控制器视图,带有一个嵌入式 collectionview 控制器。我以编程方式添加了一个右栏按钮,其中添加了一个图像,如下所示:
self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: #imageLiteral(resourceName: "greyCircle").withRenderingMode(.alwaysOriginal), style: .plain, target: self, action: #selector (handleGrayCircleButton))
我希望单击此按钮的用户能够将图像从灰色更改为银色。我将按钮处理程序设置为每次按下时从灰色切换到银色:
self.navigationItem.rightBarButtonItem?.image = UIImage(named: "greyCircle")
但是,图像在切换回来之前只会短暂更改。我试图将图像的颜色保存为“标志”变量,即如果它当前为灰色,则变为银色,以使更改持续存在,但是,图像会不断重置为加载的任何内容(与 viewDidLoad 或 viewWillAppear)。
每次点击后是否有刷新/重新加载navigationController标签栏并使其持续存在的方法,以及栏按钮的图像?
#编辑:以下是完整的按钮处理程序。
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)")
}
}
及其他功能:
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))
}