Question

弹出到不支持当前方向的视图控制器时未调用的UINavigationControllerDelegate方法。

我有一个UINavigationController作为我的应用程序的根视图控制器（我的Storyboard中的初始视图控制器）。

假设我将ViewController A推送到方向：

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

因此我们不支持任何横向模式。最重要的是，让我们使用代码推送另一个ViewController：

@interface B : UIViewController <UINavigationControllerDelegate>
@end

@implementation B
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return YES;   // any orientation supported
}

- (void)viewDidLoad {
    [super viewDidLoad];

    AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    UINavigationController *nc = (UINavigationController*)appDelegate.window.rootViewController;
    nc.delegate = self;
}

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
    // not always called...
}

- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
    // not always called...
}
@end

现在，如果我的iPhone是纵向的，我将视图控制器B推到A顶部，通过一些触摸事件，然后触摸导航栏中的“后退”按钮，一切都很好，并调用委托方法（我做那里的一些东西）。

但是，如果，当我正在查看视图B时，我旋转到横向，然后点击后退按钮，那些委托方法不会被调用!!如果有时调用方法而不调用其他方法，那么为UINavigationController设置委托有什么意义呢？当然我做错了。

我尝试将委托放在其他类中，比如AppDelegate或我的MainView，没有任何改变。

有什么想法吗？

演示代码： git://github.com/malaba/NavBarTest.git

从基本的Master-Detail模板中进行修改，如上所述。

如何表明我的观点？这是一步一步：

在主视图中添加一些行（+右上角）
然后触摸一行以转到详细信息视图
请参阅显示的登录输出
点击后退按钮（标有“Master”），再次显示日志。

现在尝试在详情视图中旋转iPhone（或模拟器），然后“返回”并看到无日志出现？！

Answer 1

嗨，这对我来说也是一个棘手的问题，直到我看到这个想法：http://www.hanspinckaers.com/custom-action-on-back-button-uinavigationcontroller

当NavigationController和TopViewController具有相同的方向时，IOS使用以下代码（monotouch）创建以下调用序列

SomeTopViewController ViewWillDisappear
WillShowViewController viewController：新的TopViewController
SomeTopViewController ViewDidDisappear
DidShowViewController viewController：新的TopViewController

当NavigationController和TopViewController具有不同的方向时，导航控制委托是不，如您所述。因此呼叫顺序是：

SomeTopViewController ViewWillDisappear
SomeTopViewController ViewDidDisappear

以下代码通过覆盖NavigationController的PopViewControllerAnimated来重现ios调用序列：

public class MyNavigationControllerDelegate : UINavigationControllerDelegate {
  public MyNavigationControllerDelegate( ) : base() {}

  public bool WasCalled {get;set;}  // flag that we use to track whether iOS calls the handlers or we have to 

  public override void WillShowViewController( UINavigationController navigationController, UIViewController viewController, bool animated ) {
    Console.WriteLine( "WillShowViewController viewController: {0}", viewController.GetType() );
    WasCalled = true;  // signal that we have been called
    //.….. do your stuff
  }

  public override void DidShowViewController( UINavigationController navigationController, UIViewController viewController, bool animated ) {
    Console.WriteLine( "DidShowViewController viewController: {0}", viewController.GetType() );
    //.….. do your stuff
  }
}

public partial class MyNavigationController : UINavigationController {
  MyNavigationControllerDelegate navigationControllerDelegate;

  public override void ViewDidLoad() {
    base.ViewDidLoad();
    navigationControllerDelegate = new MyNavigationControllerDelegate( viewSelectionControl );
    Delegate = navigationControllerDelegate;
  }

public override UIViewController PopViewControllerAnimated( bool animated ) {
  Console.WriteLine( "PopViewControllerAnimated TopViewController.GetType: {0}", TopViewController.GetType() );
  navigationControllerDelegate.WasCalled = false;   // reset flag before we start the popsequence

  UIViewController ctrl = base.PopViewControllerAnimated( animated );

  AppDelegate.MainWindow.BeginInvokeOnMainThread( delegate {
    if( !navigationControllerDelegate.WasCalled )  {   // if iOS did not call the delegate handler then we must do it
      Delegate.WillShowViewController( this, TopViewController, animated );
      navigationControllerDelegate.WasCalled = false;  // reset flag to be used in the next DidShowViewController step of the popsequence
      }
  } );

  Thread t = new Thread( () => RunPop(animated) );
  tt.Start();

  return ctrl;
}

void RunPop(bool animated) {
  Thread.Sleep( 500 );
  AppDelegate.MainWindow.BeginInvokeOnMainThread( delegate {
    if( !navigationControllerDelegate.WasCalled ) {  // if iOS did not call the delegate handler then we must do it
      Delegate.DidShowViewController(this,TopViewController,animated);
    }
  } );
}

}

Answer 2

由Kaspar回答，这是我在Obj-C中的代码。

·H：

@interface ProperNavigationController : UINavigationController

@end

@interface ProperNavigationControllerDelegate : NSObject <UINavigationControllerDelegate>
@property (assign, nonatomic) BOOL wasCalled;
@end

的.m：

#import "ProperNavigationController.h"

@interface ProperNavigationController ()
@property (strong, nonatomic) id<UINavigationControllerDelegate> oldDelegate;
@property (strong, nonatomic) ProperNavigationControllerDelegate *myDelegate;
@end

@implementation ProperNavigationController
@synthesize oldDelegate = _oldDelegate;
@synthesize myDelegate = _myDelegate;

- (void)viewDidLoad {
    [super viewDidLoad];

    self.oldDelegate = self.delegate;
    self.myDelegate = [ProperNavigationControllerDelegate new];
    self.delegate = self.myDelegate;
}

- (UIViewController *)popViewControllerAnimated:(BOOL)animated {
    self.myDelegate.wasCalled = FALSE;

    UIViewController *vc = [super popViewControllerAnimated:animated];

    if (!self.myDelegate.wasCalled) {
        // if iOS did not call the delegate handler then we must do it
        [self.myDelegate navigationController:self willShowViewController:self.topViewController animated:animated];
        [self.myDelegate navigationController:self didShowViewController:self.topViewController animated:animated];
    }

    return vc;
}

@end

@implementation ProperNavigationControllerDelegate
@synthesize wasCalled = _wasCalled;     // flag that we use to track whether iOS calls the handlers or we have to 

- (id)init {
    if (self = [super init]) {
       _wasCalled = FALSE; 
    }
    return self;
}

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
    ProperNavigationController *nc = (ProperNavigationController *)navigationController;
    [nc.oldDelegate navigationController:navigationController willShowViewController:viewController animated:animated];
    self.wasCalled = TRUE;  // signal that we have been called
}

- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
    ProperNavigationController *nc = (ProperNavigationController *)navigationController;
    [nc.oldDelegate navigationController:navigationController didShowViewController:viewController animated:animated];
}

@end

它有效。

你怎么看？我们应该填写错误报告吗？

未调用UINavigationControllerDelegate方法（github上的演示代码）

2 个答案: