[英]Load viewcontroller with nib using generics
目前要加載具有相同nibname的viewcontroller,我使用如下代碼
let recommendationVC : RecommendationVC = RecommendationVC(nibName: "RecommendationVC", bundle: nil)
我覺得指定nibname是不必要的,因為它與控制器名稱相同。 所以我決定使用泛型並使用泛型推斷類型和筆尖名稱
protocol NibIdentifiable {
static var nibNameIdentifier: String { get }
}
// MARK: - Indentifies each storyboard from its classname.
extension NibIdentifiable where Self: UIViewController {
static var nibNameIdentifier: String {
return String(describing: self)
}
}
extension UIViewController :NibIdentifiable
{
}
extension UIViewController {
func instantiate<Controller: UIViewController>(_: Controller.Type) -> Controller where Controller: NibIdentifiable {
guard let controller = Self(nibName:Controller.nibNameIdentifier,bundle:nil) as? Controller else {
fatalError("Could not dequeue cell with identifier: \(Controller.nibNameIdentifier)")
}
return controller
}
}
但在嘗試創建VC實例時,
let recommendationVC :RecommendationVC = UIViewController.instantiate()
接收錯誤無法推斷通用參數“Controller”
這種方法有什么問題?
添加UIViewController的擴展名
extension UIViewController {
static func instantiateFromNib() -> Self {
func instantiateFromNib<T: UIViewController>(_ viewType: T.Type) -> T {
return T.init(nibName: String(describing: T.self), bundle: nil)
}
return instantiateFromNib(self)
}
}
然后就這樣使用
讓myViewController = MyViewController.instantiateFromNib()
class Rec : UIViewController {
let r : String = "1231231"
}
protocol NibIdentifiable {
static var nibNameIdentifier: String { get }
}
// MARK: - Indentifies each storyboard from its classname.
extension NibIdentifiable where Self: UIViewController {
static var nibNameIdentifier: String {
return String(describing: self)
}
static func instantiate() -> Self {
guard let controller = Self(nibName:Self.nibNameIdentifier,bundle:nil) as? Self else {
fatalError("Could not dequeue cell with identifier: \(Self.nibNameIdentifier)")
}
return controller
}
}
extension UIViewController : NibIdentifiable {
}
let x : Rec = Rec.instantiate()
這必須奏效。
在我的情況下,我使用一些Storyboardable協議。 並從特定的故事板啟動Controller。
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