按下UINavigationController的后退按钮时执行操作
当按下UINavigationController的后退按钮时，我需要执行一个操作（清空一个数组），同时该按钮仍会导致堆栈上的前一个ViewController出现。我怎么能用swift完成这个？ 
29 个答案:
答案 0 :(得分：388)
按照另一个答案的建议将按钮更换为自定义按钮可能不是一个好主意，因为您将失去默认行为和样式。
另一个选择是在View Controller上实现 viewWillDisappear 方法，并检查名为 isMovingFromParentViewController 的属性。如果该属性为true，则表示视图控制器正在消失，因为它已被删除（弹出）。
应该看起来像：
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingFromParentViewController {
// Your code...
}
}
在swift 4.2中
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingFromParent {
// Your code...
}
}
答案 1 :(得分：135)
一个选项是实现您自己的自定义后退按钮。您需要将以下代码添加到viewDidLoad方法：
- (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];
}
<强>更新
以下是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：
以下是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)
}
答案 2 :(得分：48)
override func willMove(toParentViewController parent: UIViewController?)
{
super.willMove(toParentViewController: parent)
if parent == nil
{
print("This VC is 'will' be popped. i.e. the back button was pressed.")
}
}
答案 3 :(得分：28)
我创建了这个（swift）类来创建一个与常规按钮完全相同的后退按钮，包括后退箭头。它可以创建一个带有常规文本或图像的按钮。
<强>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)
}
CustomBackButtonClass
（用于绘制使用Sketch＆amp; Paintcode插件创建的后箭头的代码）
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
}
}
}
SWIFT 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
}
}
}
答案 4 :(得分：21)
我能够通过以下方式实现这一目标：
Swift 3
override func didMoveToParentViewController(parent: UIViewController?) {
super.didMoveToParentViewController(parent)
if parent == nil {
println("Back Button pressed.")
delegate?.goingBack()
}
}
Swift 4
override func didMove(toParent parent: UIViewController?) {
super.didMove(toParent: parent)
if parent == nil {
debugPrint("Back Button pressed.")
}
}
无需自定义后退按钮。
答案 5 :(得分：17)
如果您想要带后退箭头的后退按钮，可以使用下面的图像和代码
backArrow.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)
}
答案 6 :(得分：11)
如果您使用的是navigationController，请将UINavigationControllerDelegate协议添加到类中，并按如下方式添加委托方法：
class ViewController:UINavigationControllerDelegate {
func navigationController(navigationController: UINavigationController, willShowViewController viewController: UIViewController,
animated: Bool) {
if viewController === self {
// do here what you want
}
}
}
只要导航控制器滑动到新屏幕，就会调用此方法。如果按下后退按钮，则新视图控制器本身为ViewController。
答案 7 :(得分：6)
否
override func willMove(toParentViewController parent: UIViewController?) { }
即使您正在将转换为您正在覆盖此方法的视图控制器，也会调用此方法。在哪个方面检查“parent”是nil是否不是确保将移回到正确的UIViewController的确切方法。要准确确定UINavigationController是否正确导航回显示当前版本的UIViewController，您需要符合UINavigationControllerDelegate协议。
是
注意：MyViewController只是您想要检测的UIViewController的名称。
1）在文件顶部添加UINavigationControllerDelegate。
class MyViewController: UIViewController, UINavigationControllerDelegate {
2）向您的班级添加一个属性，该属性将跟踪您正在发出的UIViewController。
class MyViewController: UIViewController, UINavigationControllerDelegate {
var previousViewController:UIViewController
3）在MyViewController的{{1}}方法中指定viewDidLoad作为self的代表。
UINavigationController 3）在您离开之前，将之前的override func viewDidLoad() {
super.viewDidLoad()
self.navigationController?.delegate = self
}
指定为此属性。
UIViewController 4）并遵守// 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
}
}
}
MyViewController中的一种方法
UINavigationControllerDelegate答案 8 :(得分：5)
在Swift 5和Xcode 10.2中
请不要添加自定义栏按钮项，请使用此默认行为。
不需要 viewWillDisappear ，不需要自定义BarButtonItem 等...
最好检测何时从其父级中删除VC。
使用这两个功能中的任何一个
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
}
}
如果要停止后退按钮的默认行为，请添加自定义BarButtonItem。
答案 9 :(得分：4)
就我而言，package firefox;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.firefox.FirefoxOptions;
public class headless {
public static void main(String[] args) {
System.setProperty("webdriver.gecko.driver", "C:\\Utility\\BrowserDrivers\\geckodriver.exe");
FirefoxOptions options = new FirefoxOptions();
options.setBinary("C:\\Program Files\\Nightly\\firefox.exe");
options.addArguments("--headless");
WebDriver driver = new FirefoxDriver(options);
System.out.println("Firefox Headless Browser Invoked");
driver.get("http://www.google.com");
System.out.println("Page Title is : "+driver.getTitle());
driver.quit();
}
}
效果最好。但在某些情况下，必须修改以前的视图控制器。所以这是我的解决方案，可以访问以前的视图控制器，它适用于 Swift 4 ：
viewWillDisappear答案 10 :(得分：3)
这是我的解决方法
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
}
}
在视图控制器中，您可以像这样处理：
@objc override func shouldPopFromNavigation() -> Bool {
// Your dialog, example UIAlertViewController or whatever you want
return false
}
答案 11 :(得分：3)
我们并不困难。只需为UIButton创建一个具有清晰背景颜色的框架，为按钮指定操作并将其放在导航栏后退按钮上。最后在使用后取下按钮。
这是Swift 3 用UIImage而不是UIButton完成的示例代码
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)
}
编写需要执行的代码
func back(sender: UIBarButtonItem) {
// Perform your custom actions}
_ = self.navigationController?.popViewController(animated: true)
}
执行操作后删除子视图
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
for view in (self.navigationController?.navigationBar.subviews)!{
if view.tag == 1 {
view.removeFromSuperview()
}
}
答案 12 :(得分：2)
您可以继承UINavigationController并覆盖popViewController(animated: Bool)。除了能够执行一些代码之外，您还可以阻止用户完全返回，例如提示保存或丢弃他当前的工作。
示例实现，您可以在其中设置popHandler，该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)
}
}
会被推送的控制器设置/清除。
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
并从跟踪未保存工作的推送控制器中获取示例用法。
interactivePopGestureRecognizer作为一种很好的触摸，当用户尝试使用滑动手势返回时，select id,
max(col1) as col1,
max(col2) as col2,
max(col3) as col3
from the_table
group by id
order by id;
也会调用它。
答案 13 :(得分：2)
斯威夫特3：
override func didMove(toParentViewController parent: UIViewController?) {
super.didMove(toParentViewController: parent)
if parent == nil{
print("Back button was clicked")
}
}
答案 14 :(得分：1)
试试这个。
self.navigationItem.leftBarButtonItem?.target = "methodname"
func methodname ( ) {
// enter code here
}
试试这个。
override func viewWillAppear(animated: Bool) {
//empty your array
}
答案 15 :(得分：1)
Swift 5 __ Xcode 11.5
就我而言，我想制作动画，完成后，返回。 一种覆盖后退按钮的默认操作的方法 并调用您的自定义操作是这样的：
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)
}
}
或者您可以一次使用此方法来浏览NavigationBar视图层次结构，并获取索引以访问_UIButtonBarButton视图，强制转换为UIControl，删除target-action，并添加自定义的target-actions：
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)")
}
答案 16 :(得分：1)
Swift 4.2：
gradlew答案 17 :(得分：1)
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)
}
答案 18 :(得分：1)
根据我的理解，当您按下后退按钮并弹出以前的array时，您想要清空ViewController let {}}}您在此屏幕上加载的Array
let settingArray = NSMutableArray()
@IBAction func Back(sender: AnyObject) {
self. settingArray.removeAllObjects()
self.dismissViewControllerAnimated(true, completion: nil)
}
答案 19 :(得分：0)
按下后退按钮时，请忽略屏幕边缘手势的交互式弹出。
pip3 install pyttsx3
答案 20 :(得分：0)
这是我为自己的问题解决的方法
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) {
}
答案 21 :(得分：0)
对于 Swift 5 ，我们可以检查它是否会消失
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingFromParent {
delegate?.passValue(clickedImage: selectedImage)
}
}
答案 22 :(得分：0)
您可以简单地从堆栈中删除不必要的控制器，如下所示：
self.navigationController?.viewControllers.removeAll(where: {
$0 is FirstViewController || $0 is SecondWithPinController
})
答案 23 :(得分：0)
在离开当前控制器之前，我需要显示警报。所以我这样做：
- 使用
UINavigationController向UINavigationBarDelegate添加扩展 - 将选择器添加到控制器 navigationShouldPopOnBack（完成：）
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)
}
答案 24 :(得分：0)
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingToParent {
//your code backView
}
}
答案 25 :(得分：0)
这是最简单的Swift 5解决方案，不需要您创建自定义后退按钮并放弃免费获得的所有UINavigationController左按钮功能。
如上述 Brandon A 所建议的那样，您需要在要与其交互的视图控制器中实现UINavigationControllerDelegate，然后才能返回。一个好的方法是创建一个可以手动或自动执行的放松序列，并从自定义完成按钮或后退按钮重复使用相同的代码。
首先，在导航控制器的viewDidLoad中将感兴趣的视图控制器（您要检测的视图控制器）返回给它：
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.delegate = self
}
第二，在文件底部添加一个扩展名，以覆盖navigationController(willShow:animated:)
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)
}
}
}
}
由于您的问题中包含UITableViewController，因此我提供了一种获取用户点击的行的索引路径的方法。
答案 26 :(得分：0)
您可以在Viewcontroller中执行以下操作
override func navigationShouldPopOnBackButton() -> Bool {
self.backAction() //Your action you want to perform.
return true
}
答案 27 :(得分：0)
只需控制+将条形项拖动到func下方。像魅力一样工作
@IBAction func done(sender: AnyObject) {
if((self.presentingViewController) != nil){
self.dismiss(animated: false, completion: nil)
print("done")
}
}
答案 28 :(得分：0)
我通过调用/覆盖viewWillDisappear然后像这样访问navigationController的堆栈来完成此操作：
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
}
}
}
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