[英]Swift: refactor viewController to pass data to another controller
[英]How to pass data to another controller on dismiss ViewController?
我想將我的數據從一個ViewController
傳遞給另一個VC關閉VC。 可能嗎?
我嘗試過下一個方法但沒有成功:
點擊按鈕:
self.dismiss(animated: true) {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let controller = storyboard.instantiateViewController(withIdentifier: "EditViewController") as! EditViewController
controller.segueArray = [values]
}
當EditViewController
再次出現時,我的segueArray
就是nil
。
如何在解除時將我的數據從my ViewController
傳遞給EditViewController
?
將數據傳遞回前一個視圖控制器的最佳方法是通過委托......當從ViewController A轉到B時,將視圖控制器A作為委托傳遞,並在ViewController B的viewWillDisappear方法上,在ViewController A中調用委托方法。協議將有助於定義代理以及之前VC要實現的所需方法。 這是一個簡單的例子:
傳遞數據的協議:
protocol isAbleToReceiveData {
func pass(data: String) //data: string is an example parameter
}
Viewcontroller A:
class viewControllerA: UIViewController, isAbleToReceiveData {
func pass(data: String) { //conforms to protocol
// implement your own implementation
}
prepare(for: Segue) {
/** code for passing data **/
let vc2 = ViewCOntrollerB() /
vc2.delegate = self //sets the delegate in the new viewcontroller
//before displaying
present(vc2)
}
}
解除viewcontroller:
class viewControllerB: UIViewController {
var delegate: isAbleToReceiveData
viewWillDisappear {
delegate.pass(data: "someData") //call the func in the previous vc
}
}
在dismiss completion塊中,您將創建EditViewController的新實例。 我假設另一個EditViewController實例存在於導航堆棧中,您需要找到該實例並將segueArray設置為值。 您可以通過迭代導航堆棧的viewcontrollers來實現:
viewController.navigationController?.viewControllers.forEach({ (vc) in
if let editVC = vc as? EditViewController {
editVC.segueArray = ....
}
})
但我建議使用委托模式,如:
protocol EditViewControllerDelegate: class {
func setSegueArray(segues: [UIStoryboardSegue])
}
在viewcontroller(稱之為ViewController)中,dismiss塊是,聲明一個委托屬性:
class ViewController: UIViewController {
weak var delegate: EditViewControllerDelegate?
....
}
然后在呈現(我假設從EditViewController)ViewController的實例設置委托像:
...
if let vc = presentingViewController as? ViewController {
vc.delegate = self
}
並將EditViewController符合委托協議,如:
extension EditViewController: EditViewControllerDelegate {
func setSegueArray(segues: [UIStoryboardSegue]) {
// Do the data setting here eg. self.segues = segues
}
}
要檢測何時在視圖控制器上按下后退按鈕,我只需使用:
override func didMove(toParentViewController parent: UIViewController?) {
guard parent == nil else { return } // Back button pressed
... // Pass on the info as shown in you example
} // didMoveToParentViewController
/**
* Returns a ViewController of a class Kind
* ## Examples:
* UIView.vc(vcKind: CustomViewController.self) // ref to an instance of CustomViewController
*/
public static func vc<T: UIViewController>(vcKind: T.Type? = nil) -> T? {
guard let appDelegate = UIApplication.shared.delegate, let window = appDelegate.window else { return nil }
if let vc = window?.rootViewController as? T {
return vc
} else if let vc = window?.rootViewController?.presentedViewController as? T {
return vc
} else if let vc = window?.rootViewController?.children {
return vc.lazy.compactMap { $0 as? T }.first
}
return nil
}
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