模态视图再现+崩溃：“在过渡过程中尝试过渡”

Question

让我提供一些上下文:我正在构建一个选项卡应用程序，允许用户查找和查看托管在我们服务器上的一些视频。每个选项卡都以不同的方式对视频进行分组，导航栏中有一个分段的控件，用户可以使用该控件对列表进行更精确的排序(按标题、日期等)。当单击分段控件中的“排序”时，将在特定选项卡上显示带有可用选项的模态视图控制器。选择一个选项，并将选择转发回父视图控制器，父视图控制器在服务器上调用排序列表。

现在有个问题:在我们想要支持的iOS 4.2上，模态视图要么在选择了排序选项之后崩溃，要么退出，然后立即重新出现一次。如果它再次出现，它只会重复一次，而不会无限期地循环。我知道这与过渡和视图的生命周期有关，但我似乎不能完全理解这一点。

代码：

父视图

-(void) segmentAction:(id)sender{
    //create a sort view and pass it a value that indicates what the options should be
    ModalSortViewController *sortView = [[ModalSortViewController alloc]    
                                        initWithNibName:nil bundle:nil sortByView:0];
    [sortView setDelegate:self];
    [sortView setModalTransitionStyle:UIModalTransitionStylePartialCurl];
    [sortView setModalPresentationStyle:UIModalPresentationFormSheet];
    [self presentModalViewController:sortView animated:YES];
}

-(void) refresh:(id)sender{
    [self fetchEntries];
}

//Delegate protocol for all tabbed table views
//Receives buttonIndex from the modal sort view
-(void)sortByButtonIndex:(int)buttonIndex{

    if(buttonIndex==1){
        //If sorting by title
        fetchURL = @"fakeURL.com/?method=iGetCategories&sortBy=category&sortByOrder=ASC";
        [self fetchEntries];
    }
    else if (buttonIndex==2){
        //If sorting by number of items
        fetchURL = @"fakeURL.com/?method=iGetCategories&sortBy=count&sortByOrder=DESC";
        [self fetchEntries];
    }
    else if(buttonIndex==0){
        //Resets sort selection to nothing
        segmentedControl.selectedSegmentIndex = -1;
    }
    [self dismissModalViewControllerAnimated:YES];
}

模态观

@synthesize delegate, option1, option2;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil sortByView:(int)_viewInt
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
        sortChosen = 0;
        viewInt = _viewInt;
    }
    return self;
}

//This method is called whenever a selection on the modal view has been made.
//The button tags have been set in IB and are sent to the parent table view controller
//where a switch statement is in place to sort its data by the selection.
-(IBAction)madeSelection:(id)sender{
    sortChosen = [sender tag];
    [self.delegate sortByButtonIndex:sortChosen];
}

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];//Added after Felix pointed out that the super was not called
    switch (viewInt) {
        case CAT_FOLDERS:
            [self.option1 setTitle:@"By Category Name" forState:UIControlStateNormal];
            [self.option2 setTitle:@"By Number of Items" forState:UIControlStateNormal];
            break;

        case PRES_FOLDERS:
            [self.option1 setTitle:@"By Presenter Name" forState:UIControlStateNormal];
            [self.option2 setTitle:@"By Number of Items" forState:UIControlStateNormal];
            break;

        case MEDIA:
            [self.option1 setTitle:@"By Media Title" forState:UIControlStateNormal];
            [self.option2 setTitle:@"By Release Date" forState:UIControlStateNormal];
            break;

        default:
            break;
    }
}

崩溃结果：

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException',
reason: 'Attempting to begin a modal transition from <UINavigationController: 
0x139160> to <ModalSortViewController: 0x172810> while a transition is already in
progress. Wait for viewDidAppear/viewDidDisappear to know the current transition has completed'

很抱歉这么长。我想尽可能的清楚和彻底。提前谢谢你！

编辑:我应该提到，崩溃/重复的出现似乎取决于sortByButtonIndex:被调用的位置和视图何时被取消。

Answer 1

在我发布悬赏后的这几个小时我就能解决这个问题了！

问题是，我没有发布fetchEntries方法，因为我不认为它是罪魁祸首，当它完成对服务器的调用时，将已分段控件的选定索引设置为-1。如果iOS更改为-1，则较新版本的EventValueChanged似乎会忽略它。我只设置了一个条件来忽略segmentAction: method中分段控件上的a-1索引，它可以工作。

-(void) segmentAction:(id)sender{

    if(segmentedControl.selectedIndex != -1){
        //create a sort view and pass it a value that indicates what the options should be
        ModalSortViewController *sortView = [[ModalSortViewController alloc]    
                                        initWithNibName:nil bundle:nil sortByView:0];
        [sortView setDelegate:self];
        [sortView setModalTransitionStyle:UIModalTransitionStylePartialCurl];
        [sortView setModalPresentationStyle:UIModalPresentationFormSheet];
        [self presentModalViewController:sortView animated:YES];
    }

}

Answer 2

您不能从super内部调用-(void)viewWillAppear:(BOOL)animated。

尝试在顶部添加以下一行：

[super viewWillAppear:animated];

这可能意味着ViewController的超级实现没有正确设置它的出现标志。