'EXEC_BAD_ACCESS'在表视图中，“[TasksPageViewController tableView：numberOfRowsInSection：]”

Question

我一直在试图解决这个不良参考2天，但我找不到修复程序。

我的应用程序是一个基本的待办事项列表，包含不同类别的多个页面（UIPageControl）以及关于用户完成的任务的统计信息的第一页。 （如果您有3个类别，则最终有4个页面）。

它从NSUserDefaults加载一个类别数组，它可以通过UIButton访问的模式视图进行修改，就像在wheather应用程序中的（i）一样。

Page Control由ViewController类构建（这是主视图）。对于类别数组中的每个元素，视图控制器会生成一个新的TasksPageViewController类实例并为其实例化一个故事板视图。

一切工作正常，直到我把故事板TasksPageViewController视图UITableView并将其dataSource链接到同一类。

在TasksPageViewController中为UITableView数据源实现所需的类后，它运行良好，但是如果我尝试进入修改类别的模式视图时，按DONE（并且它应该重新加载ViewController并重建UIPageControll的许多页面），该应用程序崩溃与EXEC_BAD_ACCESS。

调试与NSZombiesEnabled，我得到：

2012-02-12 18：55：49.460 Pontinhos [25601：FE03] * - [TasksPageViewController的tableView：numberOfRowsInSection：]：消息发送到释放实例0x68c3040

但我真的不知道如何继续，我不知道哪个对象被释放，我打电话。

脚本如下：

ViewController.h

#import <UIKit/UIKit.h> 
#import "MainPageViewController.h" 
#import "TasksPageViewController.h" 

@interface ViewController : UIViewController{ 

    IBOutlet UIScrollView *scrollView; 
    IBOutlet UIPageControl *pageControl; 
    NSMutableArray * views; 

    // To be used when scrolls originate from the UIPageControl 
    BOOL pageControlUsed; 
} 

@property (nonatomic, retain) IBOutlet UIScrollView *scrollView; 
@property (nonatomic, retain) IBOutlet UIPageControl *pageControl; 
@property (nonatomic, retain) NSMutableArray *views; 

- (void)scrollViewDidScroll:(UIScrollView *)scrollView; 
- (IBAction)changePage; 

@end 

ViewController.m

#import "ViewController.h" 

@implementation ViewController 

@synthesize scrollView; 
@synthesize pageControl; 
@synthesize views; 

//carrega views que estão na array. 
- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    //LoadCategories 
    NSUserDefaults *data = [NSUserDefaults standardUserDefaults]; 
    NSMutableArray *categories = [[NSMutableArray alloc] initWithArray:[data objectForKey:@"categories"]]; 

    // MAIN PAGE 
    MainPageViewController *mainpage = [self.storyboard instantiateViewControllerWithIdentifier:@"MainPageViewController"]; 
    CGRect mframe = scrollView.frame; 
    mframe.origin.x = 0; 
    mframe.origin.y = 0; 
    mainpage.view.frame = mframe; 

    [self.scrollView addSubview:mainpage.view]; 

    int i = 1; 

    NSLog(@"Iniciando criação de páginas!"); 

    for(id name in categories) { 

     NSLog(@"Carregou página.%i",i); 
     NSLog(@"categories count:%i",[categories count]); 
     TasksPageViewController *tasks = [self.storyboard instantiateViewControllerWithIdentifier:@"TasksPageViewController"]; 

     CGRect frame = scrollView.frame; 
     frame.origin.x = frame.size.width * i; 
     frame.origin.y = 0; 
     tasks.view.frame = frame; 

     [tasks populateWithData:(i-1) categoryName:name]; 

     [scrollView addSubview:tasks.view]; 
     tasks = nil; 
     i++; 

    } 

    self.pageControl.numberOfPages = [categories count]+1; 
    self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width * ([categories count]+1), self.scrollView.frame.size.height); 

} 

- (void)scrollViewDidScroll:(UIScrollView *)scrollView { 

    if (pageControlUsed) 
    { 
     // do nothing - the scroll was initiated from the page control, not the user dragging 
     return; 
    } 

    // Update the page when more than 50% of the previous/next page is visible 
    CGFloat pageWidth = self.scrollView.frame.size.width; 
    int page = floor((self.scrollView.contentOffset.x - pageWidth/2)/pageWidth) + 1; 
    self.pageControl.currentPage = page; 
} 

- (IBAction)changePage { 
    // update the scroll view to the appropriate page 
    CGRect frame; 
    frame.origin.x = self.scrollView.frame.size.width * self.pageControl.currentPage; 
    frame.origin.y = 0; 
    frame.size = self.scrollView.frame.size; 
    [self.scrollView scrollRectToVisible:frame animated:YES]; 
    pageControlUsed = YES; 
} 


// At the begin of scroll dragging, reset the boolean used when scrolls originate from the UIPageControl 
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView 
{ 
    pageControlUsed = NO; 
} 

// At the end of scroll animation, reset the boolean used when scrolls originate from the UIPageControl 
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView 
{ 
    pageControlUsed = NO; 
} 

- (void)viewDidUnload 
{ 
    [super viewDidUnload]; 
    self.scrollView = nil; 
} 

@end 

TasksPageViewController.h

#import <UIKit/UIKit.h> 
#import "TasksTableCellPrototypes.h" 

@interface TasksPageViewController : UIViewController <UITableViewDataSource>{ 

    IBOutlet UILabel *categoryName; 
    IBOutlet UITableView *tableView; 
    //NSMutableArray *tasksData; 

} 

//@property (nonatomic,retain) NSMutableArray *tasksData; 
@property (nonatomic,retain) UITableView *tableView; 
@property (nonatomic,retain) UILabel *categoryName; 
- (void) populateWithData:(int)dataId categoryName:(NSString *)name; 

@end 

TasksPageViewControlle r.m

#import "TasksPageViewController.h" 

@implementation TasksPageViewController 

@synthesize tableView; 
//@synthesize tasksData; 
@synthesize categoryName; 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    // NSUserDefaults *data = [NSUserDefaults standardUserDefaults]; 

    //tasksData = [[NSMutableArray alloc] initWithArray:[data objectForKey:@"tasks"]]; 

    //tasksData = [[NSMutableArray alloc] initWithObjects:@"lalal",@"lololo",nil]; 

} 


- (void) populateWithData:(int)dataId categoryName:(NSString *)name { 

    //self.categoryName.text = name; 
} 

// Número de categorias 

- (NSInteger)tableView:(UITableView *)tableViewnumberOfSectionsInTableView:(UITableView *)tableView 
{ 
    // Return the number of sections. 
    return 1; 
} 



- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{ 
    NSLog(@"contou table view tasks"); 
    return 4; 
} 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{ 

    TasksTableCellPrototypes *cell = [[TasksTableCellPrototypes alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"taskCell"]; 
    return cell; 

} 

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

- (void)didReceiveMemoryWarning 
{ 
    // Releases the view if it doesn't have a superview. 
    [super didReceiveMemoryWarning]; 

    // Release any cached data, images, etc that aren't in use. 
} 


- (void)viewDidUnload 
{ 
    [super viewDidUnload]; 
    // Release any retained subviews of the main view. 
    // e.g. self.myOutlet = nil; 
} 

谢谢。

编辑：显然ViewController不保留参考TasksPageViewController和UITableView找不到它的dataSource。我真的不知道如何使用ARC来保留这一点。

Answer 1

在您的ViewController viewDidLoad中，当您循环访问类别时，您会实例化一个名为tasks的TasksPageViewController，但您不会在任何地方保留引用。因此，稍后在发送tableView:numberOfRowsInSection:消息时无法找到TasksPageViewController。

我看到在您的ViewController中，您综合了一个名为views的属性，但是您不会在任何地方使用该属性。也许你应该重命名该属性viewControllers，然后在viewDidLoad循环结束时，您应该将tasks对象添加到viewControllers可变阵列中，而不是将tasks设置为零。我认为这可能会防止崩溃。

for(id name in categories) { 

    TasksPageViewController *tasks = [self.storyboard instantiateViewControllerWithIdentifier:@"TasksPageViewController"]; 

    ... 

    [scrollView addSubview:tasks.view]; 
    [self.viewControllers addObject:tasks]; 
    i++; 

}