iphone navigationController：等待响应UIAlertView中之前退出当前

我有一个导航控制器管理的后退按钮美景，我想检查文件是否已被保存在上的后退按钮，用户点击。 如果文件已经保存你回去以前的观点，否则一个UIAlertView中询问你是否要保存文件或没有。

所以，我这样做，但鉴于disapear和alertview后出现。

-(void)viewWillDisappear:(BOOL)animated {
if(!self.fileSaved){
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"" message:@"Save the file?"  delegate:self cancelButtonTitle:@"No" otherButtonTitles:@"Yes",nil];
    [alert show];
    [alert release];
}
}

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
switch (buttonIndex) {
    case 0:
        NSLog(@"NO");
        break;
    case 1:
        NSLog(@"yes");
        break;
    default:
        break;
}
}

Answer 1:

当viewWillDisappear被调用时，它已经来不及了。 你应该早拦截上的后退按钮。 我从来没有做过，但我的建议是设置委托在你的viewDidAppear方法中的导航栏属性：

// save the previous delegate (create an ivar for that)
prevNavigationBarDelegate = self.navigationController.navigationBar.delegate;

self.navigationController.navigationBar.delegate = self;

不要忘记设置回在viewWillDisappear：

self.navigationController.navigationBar.delegate = prevNavigationBarDelegate;

然后拦截shouldPopItem方法：

- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item {
     if(!self.fileSaved) {
         UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"" message:@"Save the file?"  delegate:self cancelButtonTitle:@"No" otherButtonTitles:@"Yes",nil];
         [alert show];
         [alert release];

         return NO;
     }

   if ([prevNavigationBarDelegate respondsToSelector:@selector(navigationBar:shouldPopItem:)]) 
      return [prevNavigationBarDelegate navigationBar:navigationBar shouldPopItem:item];

   return YES; 
}

而在该对话框的是处理器，手动弹出控制器：

[self.navigationController popViewController:YES];

Answer 2:

你必须继承UINavigationController的这个工作。 然后重写 - （BOOL）的导航栏（UINavigationBar的*）的导航栏shouldPopItem：（UINavigationItem *）的项目。 你应该设置你的视图控制器采用自定义委托协议，如果你允许它弹出，请致电[超级的导航栏shouldPopItem：]，否则，返回NO上面的方法。

Answer 3:

那岂不是更容易只是左键项目添加如下所示：

UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemSave target:self action:@selector(saveThisDate)];
self.navigationItem.leftBarButtonItem = backButton;
[backButton release];

Answer 4:

为了跟进诺布雷响应和乔恩mentionned它，最好的办法是子类的UINavigationController。

最简单的方式和最快的方式来达致这：

1. 修改类的导航控制器在Interface Builder从CustomNavigationControllerDelegate继承

2. 实现在UIViewController的CustomNavigationControllerDelegate协议

@interface YourViewController <CustomNavigationControllerDelegate>

#pragma mark - UINavigationBar Delegate Methods
- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item {

    UIAlertView* alert = [[UIAlertView alloc] initWithTitle:title message:message delegate:self cancelButtonTitle:cancel otherButtonTitles:ok, nil];
    alert.tag = kpopup_back;
    [alert show];

    return NO;
}

3. 注册您的控制器作为代表

#pragma mark - viewWillAppear - (void) viewWillAppear:(BOOL)animated { ((CustomNavigationController*)self.navigationController).customDelegate = self; }

4. 最后的重要组成部分，除去委托（以避免再次触发自己的流行音乐），并弹出自己的控制器中的UIAlertViewDelegate

case kpopup_back : { if(buttonIndex != 0) //OK { ((CustomNavigationController*)self.navigationController).customDelegate = nil; [self.navigationController popViewControllerAnimated:YES]; } } break;

它完美的作品在我的身边，希望能有所帮助。

---

下面是来源：

CustomNavigationControllerDelegate.h

#import <UIKit/UIKit.h>

@protocol CustomNavigationControllerDelegate <NSObject>
@optional
- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item;
@end

@interface CustomNavigationController : UINavigationController

@property (nonatomic, retain) id<CustomNavigationControllerDelegate> customDelegate;

@end

CustomNavigationControllerDelegate.m

#import "CustomNavigationController.h"

@interface CustomNavigationController ()

@end

@implementation CustomNavigationController

- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item {

    if (_customDelegate && [_customDelegate respondsToSelector:@selector(navigationBar:shouldPopItem:)]) {
        return [_customDelegate navigationBar:navigationBar shouldPopItem:item];
    }

    return YES;
}

@end

文章来源: iphone navigationController : wait for uialertview response before to quit the current view