[英]Custom action When Pressing 'back button' on a UINavigationController
[英]Execute action when back bar button of UINavigationController is pressed
當按下UINavigationController
的后退按鈕時,我需要執行一個操作(清空數組),而該按鈕仍然會導致堆棧上的前一個ViewController
出現。 我如何使用 swift 完成此操作?
按照另一個答案的建議將按鈕替換為自定義按鈕可能不是一個好主意,因為您將失去默認行為和樣式。
另一種選擇是在視圖控制器上實現viewWillDisappear方法並檢查名為isMovingFromParentViewController的屬性。 如果該屬性為真,則意味着視圖控制器正在消失,因為它正在被移除(彈出)。
應該看起來像:
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingFromParentViewController {
// Your code...
}
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingFromParent {
// Your code...
}
}
一種選擇是實現您自己的自定義后退按鈕。 您需要將以下代碼添加到您的 viewDidLoad 方法中:
- (void) viewDidLoad {
[super viewDidLoad];
self.navigationItem.hidesBackButton = YES;
UIBarButtonItem *newBackButton = [[UIBarButtonItem alloc] initWithTitle:@"Back" style:UIBarButtonItemStyleBordered target:self action:@selector(back:)];
self.navigationItem.leftBarButtonItem = newBackButton;
}
- (void) back:(UIBarButtonItem *)sender {
// Perform your custom actions
// ...
// Go back to the previous ViewController
[self.navigationController popViewControllerAnimated:YES];
}
更新:
這是 Swift 的版本:
override func viewDidLoad {
super.viewDidLoad()
self.navigationItem.hidesBackButton = true
let newBackButton = UIBarButtonItem(title: "Back", style: UIBarButtonItemStyle.Bordered, target: self, action: "back:")
self.navigationItem.leftBarButtonItem = newBackButton
}
func back(sender: UIBarButtonItem) {
// Perform your custom actions
// ...
// Go back to the previous ViewController
self.navigationController?.popViewControllerAnimated(true)
}
更新 2:
這是 Swift 3 的版本:
override func viewDidLoad {
super.viewDidLoad()
self.navigationItem.hidesBackButton = true
let newBackButton = UIBarButtonItem(title: "Back", style: UIBarButtonItemStyle.plain, target: self, action: #selector(YourViewController.back(sender:)))
self.navigationItem.leftBarButtonItem = newBackButton
}
func back(sender: UIBarButtonItem) {
// Perform your custom actions
// ...
// Go back to the previous ViewController
_ = navigationController?.popViewController(animated: true)
}
override func willMove(toParent parent: UIViewController?)
{
super.willMove(toParent: parent)
if parent == nil
{
print("This VC is 'will' be popped. i.e. the back button was pressed.")
}
}
我能夠通過以下方式實現這一目標:
斯威夫特 3
override func didMoveToParentViewController(parent: UIViewController?) {
super.didMoveToParentViewController(parent)
if parent == nil {
println("Back Button pressed.")
delegate?.goingBack()
}
}
斯威夫特 4
override func didMove(toParent parent: UIViewController?) {
super.didMove(toParent: parent)
if parent == nil {
debugPrint("Back Button pressed.")
}
}
無需自定義后退按鈕。
我創建了這個 (swift) 類來創建一個與常規按鈕完全相同的后退按鈕,包括后退箭頭。 它可以創建帶有常規文本或圖像的按鈕。
用法
weak var weakSelf = self
// Assign back button with back arrow and text (exactly like default back button)
navigationItem.leftBarButtonItems = CustomBackButton.createWithText("YourBackButtonTitle", color: UIColor.yourColor(), target: weakSelf, action: #selector(YourViewController.tappedBackButton))
// Assign back button with back arrow and image
navigationItem.leftBarButtonItems = CustomBackButton.createWithImage(UIImage(named: "yourImageName")!, color: UIColor.yourColor(), target: weakSelf, action: #selector(YourViewController.tappedBackButton))
func tappedBackButton() {
// Do your thing
self.navigationController!.popViewControllerAnimated(true)
}
自定義返回按鈕類
(繪制使用 Sketch & Paintcode 插件創建的后退箭頭的代碼)
class CustomBackButton: NSObject {
class func createWithText(text: String, color: UIColor, target: AnyObject?, action: Selector) -> [UIBarButtonItem] {
let negativeSpacer = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FixedSpace, target: nil, action: nil)
negativeSpacer.width = -8
let backArrowImage = imageOfBackArrow(color: color)
let backArrowButton = UIBarButtonItem(image: backArrowImage, style: UIBarButtonItemStyle.Plain, target: target, action: action)
let backTextButton = UIBarButtonItem(title: text, style: UIBarButtonItemStyle.Plain , target: target, action: action)
backTextButton.setTitlePositionAdjustment(UIOffset(horizontal: -12.0, vertical: 0.0), forBarMetrics: UIBarMetrics.Default)
return [negativeSpacer, backArrowButton, backTextButton]
}
class func createWithImage(image: UIImage, color: UIColor, target: AnyObject?, action: Selector) -> [UIBarButtonItem] {
// recommended maximum image height 22 points (i.e. 22 @1x, 44 @2x, 66 @3x)
let negativeSpacer = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FixedSpace, target: nil, action: nil)
negativeSpacer.width = -8
let backArrowImageView = UIImageView(image: imageOfBackArrow(color: color))
let backImageView = UIImageView(image: image)
let customBarButton = UIButton(frame: CGRectMake(0,0,22 + backImageView.frame.width,22))
backImageView.frame = CGRectMake(22, 0, backImageView.frame.width, backImageView.frame.height)
customBarButton.addSubview(backArrowImageView)
customBarButton.addSubview(backImageView)
customBarButton.addTarget(target, action: action, forControlEvents: .TouchUpInside)
return [negativeSpacer, UIBarButtonItem(customView: customBarButton)]
}
private class func drawBackArrow(frame frame: CGRect = CGRect(x: 0, y: 0, width: 14, height: 22), color: UIColor = UIColor(hue: 0.59, saturation: 0.674, brightness: 0.886, alpha: 1), resizing: ResizingBehavior = .AspectFit) {
/// General Declarations
let context = UIGraphicsGetCurrentContext()!
/// Resize To Frame
CGContextSaveGState(context)
let resizedFrame = resizing.apply(rect: CGRect(x: 0, y: 0, width: 14, height: 22), target: frame)
CGContextTranslateCTM(context, resizedFrame.minX, resizedFrame.minY)
let resizedScale = CGSize(width: resizedFrame.width / 14, height: resizedFrame.height / 22)
CGContextScaleCTM(context, resizedScale.width, resizedScale.height)
/// Line
let line = UIBezierPath()
line.moveToPoint(CGPoint(x: 9, y: 9))
line.addLineToPoint(CGPoint.zero)
CGContextSaveGState(context)
CGContextTranslateCTM(context, 3, 11)
line.lineCapStyle = .Square
line.lineWidth = 3
color.setStroke()
line.stroke()
CGContextRestoreGState(context)
/// Line Copy
let lineCopy = UIBezierPath()
lineCopy.moveToPoint(CGPoint(x: 9, y: 0))
lineCopy.addLineToPoint(CGPoint(x: 0, y: 9))
CGContextSaveGState(context)
CGContextTranslateCTM(context, 3, 2)
lineCopy.lineCapStyle = .Square
lineCopy.lineWidth = 3
color.setStroke()
lineCopy.stroke()
CGContextRestoreGState(context)
CGContextRestoreGState(context)
}
private class func imageOfBackArrow(size size: CGSize = CGSize(width: 14, height: 22), color: UIColor = UIColor(hue: 0.59, saturation: 0.674, brightness: 0.886, alpha: 1), resizing: ResizingBehavior = .AspectFit) -> UIImage {
var image: UIImage
UIGraphicsBeginImageContextWithOptions(size, false, 0)
drawBackArrow(frame: CGRect(origin: CGPoint.zero, size: size), color: color, resizing: resizing)
image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
private enum ResizingBehavior {
case AspectFit /// The content is proportionally resized to fit into the target rectangle.
case AspectFill /// The content is proportionally resized to completely fill the target rectangle.
case Stretch /// The content is stretched to match the entire target rectangle.
case Center /// The content is centered in the target rectangle, but it is NOT resized.
func apply(rect rect: CGRect, target: CGRect) -> CGRect {
if rect == target || target == CGRect.zero {
return rect
}
var scales = CGSize.zero
scales.width = abs(target.width / rect.width)
scales.height = abs(target.height / rect.height)
switch self {
case .AspectFit:
scales.width = min(scales.width, scales.height)
scales.height = scales.width
case .AspectFill:
scales.width = max(scales.width, scales.height)
scales.height = scales.width
case .Stretch:
break
case .Center:
scales.width = 1
scales.height = 1
}
var result = rect.standardized
result.size.width *= scales.width
result.size.height *= scales.height
result.origin.x = target.minX + (target.width - result.width) / 2
result.origin.y = target.minY + (target.height - result.height) / 2
return result
}
}
}
斯威夫特 3.0
class CustomBackButton: NSObject {
class func createWithText(text: String, color: UIColor, target: AnyObject?, action: Selector) -> [UIBarButtonItem] {
let negativeSpacer = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.fixedSpace, target: nil, action: nil)
negativeSpacer.width = -8
let backArrowImage = imageOfBackArrow(color: color)
let backArrowButton = UIBarButtonItem(image: backArrowImage, style: UIBarButtonItemStyle.plain, target: target, action: action)
let backTextButton = UIBarButtonItem(title: text, style: UIBarButtonItemStyle.plain , target: target, action: action)
backTextButton.setTitlePositionAdjustment(UIOffset(horizontal: -12.0, vertical: 0.0), for: UIBarMetrics.default)
return [negativeSpacer, backArrowButton, backTextButton]
}
class func createWithImage(image: UIImage, color: UIColor, target: AnyObject?, action: Selector) -> [UIBarButtonItem] {
// recommended maximum image height 22 points (i.e. 22 @1x, 44 @2x, 66 @3x)
let negativeSpacer = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.fixedSpace, target: nil, action: nil)
negativeSpacer.width = -8
let backArrowImageView = UIImageView(image: imageOfBackArrow(color: color))
let backImageView = UIImageView(image: image)
let customBarButton = UIButton(frame: CGRect(x: 0, y: 0, width: 22 + backImageView.frame.width, height: 22))
backImageView.frame = CGRect(x: 22, y: 0, width: backImageView.frame.width, height: backImageView.frame.height)
customBarButton.addSubview(backArrowImageView)
customBarButton.addSubview(backImageView)
customBarButton.addTarget(target, action: action, for: .touchUpInside)
return [negativeSpacer, UIBarButtonItem(customView: customBarButton)]
}
private class func drawBackArrow(_ frame: CGRect = CGRect(x: 0, y: 0, width: 14, height: 22), color: UIColor = UIColor(hue: 0.59, saturation: 0.674, brightness: 0.886, alpha: 1), resizing: ResizingBehavior = .AspectFit) {
/// General Declarations
let context = UIGraphicsGetCurrentContext()!
/// Resize To Frame
context.saveGState()
let resizedFrame = resizing.apply(CGRect(x: 0, y: 0, width: 14, height: 22), target: frame)
context.translateBy(x: resizedFrame.minX, y: resizedFrame.minY)
let resizedScale = CGSize(width: resizedFrame.width / 14, height: resizedFrame.height / 22)
context.scaleBy(x: resizedScale.width, y: resizedScale.height)
/// Line
let line = UIBezierPath()
line.move(to: CGPoint(x: 9, y: 9))
line.addLine(to: CGPoint.zero)
context.saveGState()
context.translateBy(x: 3, y: 11)
line.lineCapStyle = .square
line.lineWidth = 3
color.setStroke()
line.stroke()
context.restoreGState()
/// Line Copy
let lineCopy = UIBezierPath()
lineCopy.move(to: CGPoint(x: 9, y: 0))
lineCopy.addLine(to: CGPoint(x: 0, y: 9))
context.saveGState()
context.translateBy(x: 3, y: 2)
lineCopy.lineCapStyle = .square
lineCopy.lineWidth = 3
color.setStroke()
lineCopy.stroke()
context.restoreGState()
context.restoreGState()
}
private class func imageOfBackArrow(_ size: CGSize = CGSize(width: 14, height: 22), color: UIColor = UIColor(hue: 0.59, saturation: 0.674, brightness: 0.886, alpha: 1), resizing: ResizingBehavior = .AspectFit) -> UIImage {
var image: UIImage
UIGraphicsBeginImageContextWithOptions(size, false, 0)
drawBackArrow(CGRect(origin: CGPoint.zero, size: size), color: color, resizing: resizing)
image = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return image
}
private enum ResizingBehavior {
case AspectFit /// The content is proportionally resized to fit into the target rectangle.
case AspectFill /// The content is proportionally resized to completely fill the target rectangle.
case Stretch /// The content is stretched to match the entire target rectangle.
case Center /// The content is centered in the target rectangle, but it is NOT resized.
func apply(_ rect: CGRect, target: CGRect) -> CGRect {
if rect == target || target == CGRect.zero {
return rect
}
var scales = CGSize.zero
scales.width = abs(target.width / rect.width)
scales.height = abs(target.height / rect.height)
switch self {
case .AspectFit:
scales.width = min(scales.width, scales.height)
scales.height = scales.width
case .AspectFill:
scales.width = max(scales.width, scales.height)
scales.height = scales.width
case .Stretch:
break
case .Center:
scales.width = 1
scales.height = 1
}
var result = rect.standardized
result.size.width *= scales.width
result.size.height *= scales.height
result.origin.x = target.minX + (target.width - result.width) / 2
result.origin.y = target.minY + (target.height - result.height) / 2
return result
}
}
}
如果您想使用帶有后退箭頭的后退按鈕,您可以使用下面的圖片和代碼
返回箭頭.png backArrow@2x.png backArrow@3x.png
override func viewDidLoad() {
super.viewDidLoad()
let customBackButton = UIBarButtonItem(image: UIImage(named: "backArrow") , style: .plain, target: self, action: #selector(backAction(sender:)))
customBackButton.imageInsets = UIEdgeInsets(top: 2, left: -8, bottom: 0, right: 0)
navigationItem.leftBarButtonItem = customBackButton
}
func backAction(sender: UIBarButtonItem) {
// custom actions here
navigationController?.popViewController(animated: true)
}
在 Swift 5 和 Xcode 10.2 中
請不要添加自定義欄按鈕項,請使用此默認行為。
不需要viewWillDisappear ,不需要自定義 BarButtonItem等...
最好檢測 VC 何時從其父級中刪除。
使用這兩個函數中的任何一個
override func willMove(toParent parent: UIViewController?) {
super.willMove(toParent: parent)
if parent == nil {
callStatusDelegate?.backButtonClicked()//Here write your code
}
}
override func didMove(toParent parent: UIViewController?) {
super.didMove(toParent: parent)
if parent == nil {
callStatusDelegate?.backButtonClicked()//Here write your code
}
}
如果您想停止后退按鈕的默認行為,請添加自定義 BarButtonItem。
如果您使用的是navigationController
則將UINavigationControllerDelegate
協議添加到類並添加委托方法,如下所示:
class ViewController:UINavigationControllerDelegate {
func navigationController(navigationController: UINavigationController, willShowViewController viewController: UIViewController,
animated: Bool) {
if viewController === self {
// do here what you want
}
}
}
每當導航控制器滑動到新屏幕時都會調用此方法。 如果按下后退按鈕,新的視圖控制器就是ViewController
本身。
不
override func willMove(toParentViewController parent: UIViewController?) { }
這將被調用,即使你是segueing到視圖控制器中你重寫此方法。 其中檢查“ parent
”是否nil
不是確保移回正確的UIViewController
的精確方法。 要准確確定UINavigationController
是否正確導航回呈現當前的UIViewController
,您需要遵守UINavigationControllerDelegate
協議。
是的
注意: MyViewController
只是您要檢測返回的任何UIViewController
的名稱。
1) 在文件頂部添加UINavigationControllerDelegate
。
class MyViewController: UIViewController, UINavigationControllerDelegate {
2)向您的類添加一個屬性,該屬性將跟蹤您正在從中分離的UIViewController
。
class MyViewController: UIViewController, UINavigationControllerDelegate {
var previousViewController:UIViewController
3) 在MyViewController
的viewDidLoad
方法中,將self
指定為UINavigationController
的委托。
override func viewDidLoad() {
super.viewDidLoad()
self.navigationController?.delegate = self
}
3)在segue 之前,將之前的UIViewController
分配為此屬性。
// In previous UIViewController
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "YourSegueID" {
if let nextViewController = segue.destination as? MyViewController {
nextViewController.previousViewController = self
}
}
}
4) 並符合UINavigationControllerDelegate
MyViewController
中的一種方法
func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
if viewController == self.previousViewController {
// You are going back
}
}
就我而言, viewWillDisappear
效果最好。 但在某些情況下,必須修改以前的視圖控制器。 所以這是我可以訪問以前的視圖控制器的解決方案,它適用於Swift 4 :
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if isMovingFromParentViewController {
if let viewControllers = self.navigationController?.viewControllers {
if (viewControllers.count >= 1) {
let previousViewController = viewControllers[viewControllers.count-1] as! NameOfDestinationViewController
// whatever you want to do
previousViewController.callOrModifySomething()
}
}
}
}
在離開當前控制器之前,我需要顯示警報。 所以我是這樣做的:
UINavigationBarDelegate
向UINavigationController
添加擴展成功了)
extension UINavigationController: UINavigationBarDelegate {
public func navigationBar(_ navigationBar: UINavigationBar, shouldPop item: UINavigationItem) -> Bool {
if let items = navigationBar.items, viewControllers.count < items.count {
return true
}
let clientInfoVC = topViewController as? ClientInfoVC
if clientInfoVC?.responds(to: #selector(clientInfoVC?.navigationShouldPopOnBack)) ?? false {
clientInfoVC?.navigationShouldPopOnBack(completion: { isAllowPop in
if isAllowPop {
DispatchQueue.main.async {
self.popViewController(animated: true)
}
}
})
}
DispatchQueue.main.async {
self.popViewController(animated: true)
}
return false
}
}
@objc func navigationShouldPopOnBack(completion: @escaping (Bool) -> ()) {
let ok = UIAlertAction(title: R.string.alert.actionOk(), style: .default) { _ in
completion(true)
}
let cancel = UIAlertAction(title: R.string.alert.actionCancel(), style: .cancel) { _ in
completion(false)
}
let alertController = UIAlertController(title: "", message: R.string.alert.contractMessage(), preferredStyle: .alert)
alertController.addAction(ok)
alertController.addAction(cancel)
present(alertController, animated: true, completion: nil)
}
我們的事情並不難。 只需為 UIButton 創建一個具有清晰背景顏色的框架,為按鈕分配操作並放置在導航欄后退按鈕上。 最后在使用后取下按鈕。
這是使用 UIImage 而不是 UIButton 完成的 Swift 3 示例代碼
override func viewDidLoad() {
super.viewDidLoad()
let imageView = UIImageView()
imageView.backgroundColor = UIColor.clear
imageView.frame = CGRect(x:0,y:0,width:2*(self.navigationController?.navigationBar.bounds.height)!,height:(self.navigationController?.navigationBar.bounds.height)!)
let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(back(sender:)))
imageView.isUserInteractionEnabled = true
imageView.addGestureRecognizer(tapGestureRecognizer)
imageView.tag = 1
self.navigationController?.navigationBar.addSubview(imageView)
}
編寫需要執行的代碼
func back(sender: UIBarButtonItem) {
// Perform your custom actions}
_ = self.navigationController?.popViewController(animated: true)
}
執行操作后刪除子視圖
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
for view in (self.navigationController?.navigationBar.subviews)!{
if view.tag == 1 {
view.removeFromSuperview()
}
}
對於Swift 5 ,我們可以在視圖中檢查它是否會消失
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingFromParent {
delegate?.passValue(clickedImage: selectedImage)
}
}
這是我的解決方案
extension UINavigationController: UINavigationBarDelegate {
public func navigationBar(_ navigationBar: UINavigationBar, shouldPop item: UINavigationItem) -> Bool {
if let shouldBlock = self.topViewController?.shouldPopFromNavigation() {
return shouldBlock
}
return true
}
}
extension UIViewController {
@objc func shouldPopFromNavigation() -> Bool {
return true
}
}
在您的視圖控制器中,您可以這樣處理:
@objc override func shouldPopFromNavigation() -> Bool {
// Your dialog, example UIAlertViewController or whatever you want
return false
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingFromParent {
// Your code...
}
}
斯威夫特 3:
override func didMove(toParentViewController parent: UIViewController?) {
super.didMove(toParentViewController: parent)
if parent == nil{
print("Back button was clicked")
}
}
您可以popViewController(animated: Bool)
UINavigationController
並覆蓋popViewController(animated: Bool)
。 除了能夠在那里執行一些代碼之外,您還可以防止用戶完全返回,例如提示保存或放棄他當前的工作。
示例實現,您可以在其中設置由推送控制器設置/清除的popHandler
。
class NavigationController: UINavigationController
{
var popHandler: (() -> Bool)?
override func popViewController(animated: Bool) -> UIViewController?
{
guard self.popHandler?() != false else
{
return nil
}
self.popHandler = nil
return super.popViewController(animated: animated)
}
}
以及來自跟蹤未保存工作的推送控制器的示例用法。
let hasUnsavedWork: Bool = // ...
(self.navigationController as! NavigationController).popHandler = hasUnsavedWork ?
{
// Prompt saving work here with an alert
return false // Prevent pop until as user choses to save or discard
} : nil // No unsaved work, we clear popHandler to let it pop normally
作為一個很好的接觸,當用戶嘗試使用滑動手勢返回時, interactivePopGestureRecognizer
也會調用它。
override public func viewDidLoad() {
super.viewDidLoad()
self.navigationController?.navigationBar.topItem?.title = GlobalVariables.selectedMainIconName
let image = UIImage(named: "back-btn")
image = image?.imageWithRenderingMode(UIImageRenderingMode.AlwaysOriginal)
self.navigationItem.leftBarButtonItem = UIBarButtonItem(image: image, style: UIBarButtonItemStyle.Plain, target: self, action: #selector(Current[enter image description here][1]ViewController.back) )
}
func back() {
self.navigationController?.popToViewController( self.navigationController!.viewControllers[ self.navigationController!.viewControllers.count - 2 ], animated: true)
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingToParent {
//your code backView
}
}
在我的例子中,我想制作一個動畫,當它完成時,回去。 覆蓋后退按鈕的默認操作並調用自定義操作的方法是:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
setBtnBack()
}
private func setBtnBack() {
for vw in navigationController?.navigationBar.subviews ?? [] where "\(vw.classForCoder)" == "_UINavigationBarContentView" {
print("\(vw.classForCoder)")
for subVw in vw.subviews where "\(subVw.classForCoder)" == "_UIButtonBarButton" {
let ctrl = subVw as! UIControl
ctrl.removeTarget(ctrl.allTargets.first, action: nil, for: .allEvents)
ctrl.addTarget(self, action: #selector(backBarBtnAction), for: .touchUpInside)
}
}
}
@objc func backBarBtnAction() {
doSomethingBeforeBack { [weak self](isEndedOk) in
if isEndedOk {
self?.navigationController?.popViewController(animated: true)
}
}
}
private func doSomethingBeforeBack(completion: @escaping (_ isEndedOk:Bool)->Void ) {
UIView.animate(withDuration: 0.25, animations: { [weak self] in
self?.vwTxt.alpha = 0
}) { (isEnded) in
completion(isEnded)
}
}
或者您可以使用此方法一次探索 NavigationBar 視圖層次結構,並獲取索引以訪問 _UIButtonBarButton 視圖,轉換為 UIControl,刪除目標操作,並添加您的自定義目標操作:
private func debug_printSubviews(arrSubviews:[UIView]?, level:Int) {
for (i,subVw) in (arrSubviews ?? []).enumerated() {
var str = ""
for _ in 0...level {
str += "\t"
}
str += String(format: "%2d %@",i, "\(subVw.classForCoder)")
print(str)
debug_printSubviews(arrSubviews: subVw.subviews, level: level + 1)
}
}
// Set directly the indexs
private func setBtnBack_method2() {
// Remove or comment the print lines
debug_printSubviews(arrSubviews: navigationController?.navigationBar.subviews, level: 0)
let ctrl = navigationController?.navigationBar.subviews[1].subviews[0] as! UIControl
print("ctrl.allTargets: \(ctrl.allTargets)")
ctrl.removeTarget(ctrl.allTargets.first, action: nil, for: .allEvents)
print("ctrl.allTargets: \(ctrl.allTargets)")
ctrl.addTarget(self, action: #selector(backBarBtnAction), for: .touchUpInside)
print("ctrl.allTargets: \(ctrl.allTargets)")
}
嘗試這個 。
self.navigationItem.leftBarButtonItem?.target = "methodname"
func methodname ( ) {
// enter code here
}
也試試這個。
override func viewWillAppear(animated: Bool) {
//empty your array
}
據我了解,當您按下后退按鈕並彈出到之前的ViewController let
您想清空array
, ViewController let
您在此屏幕上加載的Array
是
let settingArray = NSMutableArray()
@IBAction func Back(sender: AnyObject) {
self. settingArray.removeAllObjects()
self.dismissViewControllerAnimated(true, completion: nil)
}
當按下后退按鈕時,忽略屏幕邊緣手勢的交互彈出。
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if isMovingFromParent, transitionCoordinator?.isInteractive == false {
// code here
}
}
我通過調用/覆蓋viewWillDisappear
然后像這樣訪問navigationController
的堆棧來完成此操作:
override func viewWillDisappear(animated: Bool) {
super.viewWillDisappear(animated)
let stack = self.navigationController?.viewControllers.count
if stack >= 2 {
// for whatever reason, the last item on the stack is the TaskBuilderViewController (not self), so we only use -1 to access it
if let lastitem = self.navigationController?.viewControllers[stack! - 1] as? theViewControllerYoureTryingToAccess {
// hand over the data via public property or call a public method of theViewControllerYoureTryingToAccess, like
lastitem.emptyArray()
lastitem.value = 5
}
}
}
你可以在你的 Viewcontroller 中做一些事情
override func navigationShouldPopOnBackButton() -> Bool {
self.backAction() //Your action you want to perform.
return true
}
要獲得完整的答案,請使用檢測何時在導航欄上按下“后退”按鈕
這是最簡單的 Swift 5 解決方案,它不需要您創建自定義后退按鈕並放棄您免費獲得的所有 UINavigationController 左按鈕功能。
正如上面Brandon A 所建議的,在返回之前,您需要在要與之交互的視圖控制器中實現UINavigationControllerDelegate
。 一個好方法是創建一個可以手動或自動執行的 unwind segue,並重用來自自定義完成按鈕或后退按鈕的相同代碼。
首先,讓您感興趣的視圖控制器(您想要檢測返回的視圖控制器)成為其viewDidLoad
導航控制器的委托:
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.delegate = self
}
其次,在文件底部添加一個覆蓋navigationController(willShow:animated:)
的擴展名
extension PickerTableViewController: UINavigationControllerDelegate {
func navigationController(_ navigationController: UINavigationController,
willShow viewController: UIViewController,
animated: Bool) {
if let _ = viewController as? EditComicBookViewController {
let selectedItemRow = itemList.firstIndex(of: selectedItemName)
selectedItemIndex = IndexPath(row: selectedItemRow!, section: 0)
if let selectedCell = tableView.cellForRow(at: selectedItemIndex) {
performSegue(withIdentifier: "PickedItem", sender: selectedCell)
}
}
}
}
由於您的問題包括UITableViewController
,因此我提供了一種獲取用戶點擊的行的索引路徑的方法。
嘗試稱呼這個
override func viewDidDisappear(_ animated: Bool) {
super.viewDidDisappear(animated)
if self.isMovingFromParent {
print("isMovingFromParent()") // dismiss for push viewController
}
if self.isBeingDismissed {
print("isBeingDismissed()") // dismiss for modal that doesn't has navigationController
}
if self.navigationController?.isBeingDismissed ?? false {
print("navigationController?.isBeingDismissed()") // dismiss for modal that has navigationController
}
}
我的偏好是覆蓋導航 Controller 中的 popViewController。 這樣做的好處是:
First, create a custom Navigation Controller class (and be sure to assign it to the Navigation Controller in your Story Board or wherever your navigation controller is created):
class NavControllerWithBackButtonOverride: UINavigationController {
var backButtonOverride: (() -> Void)? = nil
override func popViewController(animated: Bool) -> UIViewController? {
if backButtonOverride != nil {
//if anything is assigned to the backButtonOverride the override will run
self.backButtonOverride!()
return nil
} else {
//otherwise the default popViewController will run
return super.popViewController(animated: animated)
}
}
}
然后通過為 backButtonOverride 變量賦值來啟用/禁用 View Controller 中的覆蓋:
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.enableCustomBackButton()
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
self.disableCustomBackButton()
}
/**
Custom Back Button
*/
func customBackButtonAction() {
print("DO THIS INSTEAD")
}
func enableCustomBackButton() {
if let nav = self.navigationController as? NavControllerWithBackButtonOverride {
nav.backButtonOverride = { self.customBackButtonAction() }
nav.interactivePopGestureRecognizer?.isEnabled = false
}
}
func disableCustomBackButton() {
if let nav = self.navigationController as? NavControllerWithBackButtonOverride {
nav.backButtonOverride = nil
nav.interactivePopGestureRecognizer?.isEnabled = true
}
}
注意:我還禁用了 interactivePopGestureRecognizer,因為它會導致自定義設置出現問題。
Swift 5+(帶警報控件的后退按鈕)
override func viewDidLoad() {
super.viewDidLoad()
self.navigationItem.hidesBackButton = true
let newBackButton = UIBarButtonItem(title: "<Back", style: UIBarButtonItem.Style.plain, target: self, action: #selector(PGWebViewController.back(sender:)))
self.navigationItem.leftBarButtonItem = newBackButton
}
@objc func back(sender: UIBarButtonItem) {
let alert = UIAlertController(title: "Warning!", message: "Your payment process is not completed yet. Do you want to go back?", preferredStyle: .alert)
let ok = UIAlertAction(title: "OK", style: .default, handler: { action in
_ = self.navigationController?.popViewController(animated: true)
})
alert.addAction(ok)
let cancel = UIAlertAction(title: "Cancel", style: .default, handler: { action in
})
alert.addAction(cancel)
DispatchQueue.main.async(execute: {
self.present(alert, animated: true)
})}
這就是我為自己的問題解決的方法
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.navigationItem.leftBarButtonItem?.action = #selector(self.back(sender:))
self.navigationItem.leftBarButtonItem?.target = self
}
@objc func back(sender: UIBarButtonItem) {
}
您可以簡單地從堆棧中刪除不必要的控制器,如下所示:
self.navigationController?.viewControllers.removeAll(where: {
$0 is FirstViewController || $0 is SecondWithPinController
})
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