iphone - 关闭 ViewController : not working

Question

我有一个名为 vc0 的 View Controller ，它是这样显示的:

[self presentViewController: vc1 animated: YES completion: nil];

在 vc1 中我有一个按钮来呈现另一个 View Controller :

[self presentViewController: vc2 animated: YES completion: nil];

然后在 vc2 中，我有一个关闭 View Controller 的按钮:

[self dismissViewControllerAnimated:YES completion: ^{
// over here I call one method in vc1
}

正如预期的那样，它返回到 vc1.. 然而，在 vc1 中有一个按钮可以通过关闭 View Controller 返回到 vc0，如下所示:

    [self dismissViewControllerAnimated:YES completion:nil];

但由于某种原因它不起作用， View Controller 不会被解散回 vc0。当我第一次展示 vc1 时，我可以按下按钮关闭 View Controller 并且它可以工作。但是当我按下按钮打开 vc2，当我关闭 vc2 回到 vc1，然后我按下按钮关闭 View Controller 时，它就不起作用了。

抱歉，如果问题有点不清楚，我很难表达我想说的话。

还有一件事:

我尝试替换 vc1 中的 dismissViewControllerAnimated: 以手动呈现 vc0，但随后我在控制台中收到一条日志，指出我正在尝试呈现 vc0，但 vc1 的 View 不在窗口层次结构中。这是什么意思？

感谢您的帮助!

更新:

在这种情况下，VC0 是 MenuMileIndexViewController - VC1 是 FlightViewController - VC2 是 BookmarksTableViewController

这里是涉及的代码:

MenuMileIndexViewController:

- (IBAction)goToOriginPage {

FlightRecorder *origin = [[FlightRecorder alloc] init];
[self presentViewController:origin animated:YES completion:nil];

}

Flight Recorder:

    - (void)searchBarBookmarkButtonClicked:(UISearchBar *)searchBar {

        [self bringUpBookmarkkTable];
}

- (void) bringUpBookmarkkTable {

    BookmarkTableViewController *bookmarkTVC = [[BookmarkTableViewController alloc] init];

    [bookmarkTVC setModalTransitionStyle: UIModalTransitionStyleFlipHorizontal];

    [self presentViewController:bookmarkTVC animated:YES completion:nil];
}

- (IBAction)cancel {

[self dismissViewControllerAnimated:YES completion:nil];

}

- (void)endBookmarkProcessWithBookmarkCollection: (NSDictionary *)dict {

    presetBookmarkContext = [dict mutableCopy];

    bookmarkMode = YES;

    NSString *compiledText = nil;

    NSNumber *number1 = [NSNumber numberWithInt: 1];

    if ([dict objectForKey: @"bookmarkTag"] == number1) {

        compiledText = [NSString stringWithFormat: @"%@ to %@", [dict objectForKey: @"origin"], [dict objectForKey: @"destination"]];
    }
    else {

        compiledText = [NSString stringWithFormat: @"%@ to %@", [dict objectForKey: @"destination"], [dict objectForKey: @"origin"]];
    }

    compiledText = [compiledText stringByReplacingOccurrencesOfString:@"Origin: " withString:@""];

    compiledText = [compiledText stringByReplacingOccurrencesOfString:@"Destination: " withString:@""];

    flightContext = [NSDictionary dictionaryWithObjectsAndKeys: [dict objectForKey: @"miles"], @"miles", compiledText, @"location", [[NSUserDefaults standardUserDefaults] objectForKey: @"tempD"], @"date", nil];

    NSString *string = [NSString stringWithFormat: @"\nMiles: %.2f\nFlight: %@\nDate: %@", [[dict objectForKey: @"miles"] floatValue], compiledText, [[NSUserDefaults standardUserDefaults] objectForKey:@"tempD"]];

    UIAlertView *bvkBookmarkAlertView = [[UIAlertView alloc] initWithTitle:@"Confirmation" message:string delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Add", nil];

    [bvkBookmarkAlertView show];
}



 - (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex {

    if (buttonIndex == 1) {

        [self cancel]; // Even though cancel is an IBAction, IBAction is the same thing as void so it is callable
    }
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {

    if (buttonIndex == 1) {

        [TheMileIndexViewController addDesiredMilesToIndex: [[flightContext objectForKey: @"miles"] doubleValue]];

        [TravelLogViewController addFlight: flightContext];

        if (!bookmarkMode) {

            if ([checkbox isSelected]) {

                [BookmarkHandler uploadBookmark: bookmarkFlightContext];
            }    
        }
    }

    if (buttonIndex == 0) {

        if ([alertView.title isEqualToString: @"Confirmation"]) {

            bookmarkMode = NO;
        }
    }

}

BookmarksTableViewController:

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    [tableView deselectRowAtIndexPath:indexPath animated: YES];

    NSDictionary *dict = [[BookmarkHandler bookmarkCollection] objectAtIndex: indexPath.row];

    fl = [[FlightRecorder alloc] init];

    [self dismissViewControllerAnimated:YES completion:^{

        [fl endBookmarkProcessWithBookmarkCollection: dict];
    }];
}

现在，我已经在模拟器中创建了应用程序的屏幕录像，显示出了什么问题。我可以通过电子邮件将其发送给您以供引用。这样我就可以通过电子邮件将其发送给您。

Answer 1

我建议始终从实际呈现它的 VC 中解雇 VC - 使用委托(delegate)。这实际上也是 Apple 推荐的方式 - 正如我之前对有关此问题的问题的回答所指出的那样。

因此，如果您有 VC0 呈现 VC1，则在 VC0 中也有关闭 VC1 代码，使用委托(delegate)方案。

我了解到这是处理呈现和解散的最省事的方法 - 尽管有时它可以在 VC1 本身中解散 VC1。

我问了一个非常相关的问题，您可能也有兴趣检查一下。它显示 code...

ps 我还读到有些人只拒绝 VC1 - 这反过来也会拒绝 VC2。但是，如果我之前的建议有效，我不会这样做。有时我在执行过程中得到信息(没有崩溃)，VC 不再存在或与之相关的任何东西 - 所以我认为这不是最好的解决方案。但如果我之前的建议不起作用，你可以试试第二个。

虽然不能保证这会持续到新 iOS 的更新，因为这个问题现在一直困扰着我几个 iOS 更新 :-)，所以我决定采用标准的推荐路线。

编辑:这是我修改后的代码 - 它可以正常工作 - 但是不清楚你打算在用户响应警报后发生什么以及警报应该在 VC1 还是 VC0 上。无论如何使用委托(delegate)和回调我没有看到任何问题。请解释我是否错过了你的观点......

FlightViewControllerProtocol.h

@protocol FlightViewControllerProtocol <NSObject>
-(void) dismissVCAndEndBookmark;
@end

FlightViewController.m

#import "FlightViewController.h"
#import "FlightViewControllerProtocol.h"
#import "BookmarksTableViewController.h"
@interface FlightViewController ()

@end

@implementation FlightViewController
@synthesize delegate;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)searchBarBookmarkButtonClicked:(UISearchBar *)searchBar {

    [self bringUpBookmarkkTable];
}

- (IBAction) bringUpBookmarkkTable {

    BookmarksTableViewController *bookmarkTVC = [[BookmarksTableViewController alloc] init];
    bookmarkTVC.delegate = self;
    [bookmarkTVC setModalTransitionStyle: UIModalTransitionStyleFlipHorizontal];

    [self presentViewController:bookmarkTVC animated:YES completion:nil];
}

- (IBAction)cancel {

    [self dismissViewControllerAnimated:YES completion:nil];

}

- (void)endBookmarkProcessWithBookmarkCollection: (NSDictionary *)dict {

//    presetBookmarkContext = [dict mutableCopy];

//    bookmarkMode = YES;

    NSString *compiledText = nil;

    NSNumber *number1 = [NSNumber numberWithInt: 1];

    if ([dict objectForKey: @"bookmarkTag"] == number1) {

        compiledText = @"Text1";
    }
    else {
        compiledText = @"Text2";
    }


//    flightContext = [NSDictionary dictionaryWithObjectsAndKeys: [dict objectForKey: @"miles"], @"miles", compiledText, @"location", [[NSUserDefaults standardUserDefaults] objectForKey: @"tempD"], @"date", nil];

    NSString *string = compiledText;

    UIAlertView *bvkBookmarkAlertView = [[UIAlertView alloc] initWithTitle:@"Confirmation" message:string delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Add", nil];

    [bvkBookmarkAlertView show];
}


- (void) dismissVCAndEndBookmark {
    [self dismissViewControllerAnimated:YES completion:nil];
     [self endBookmarkProcessWithBookmarkCollection: nil];
}

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex {

    if (buttonIndex == 1) {

        [self cancel]; // Even though cancel is an IBAction, IBAction is the same thing as void so it is callable
    }
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {

    if (buttonIndex == 1) {

        NSLog(@"alertView1");
           }

    if (buttonIndex == 0) {
        NSLog(@"alertView2");

    }

}

@end

书签TableViewController.h

 @interface BookmarksTableViewController : UIViewController
{
    id delegate;
}

@property (nonatomic,strong)   id delegate;

@end

BookmarksTableViewController.m

- (IBAction)goBack {
    [self.delegate dismissVCAndEndBookmark];
}

如果我正确理解您的意图，Esp BookmarksTableViewController.m 中的回调似乎是您实现中的主要问题。