无法将NSMutableArray添加到

我以前遇到过这种问题,但没有得到满意的答案。

我通过了 NSMutableArray *counties 当我将第二个控制器推到导航堆栈上时。实际上,我设置了第二个控制器的“selectedCounties”属性(也是一个NSMutableArray),指针指向第一个控制器的“counties”,如下所示。

当我去 addObject 不过,我明白了:

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '*** -[NSCFArray insertObject:atIndex:]: mutating method sent to immutable object'

这是我的密码:

在SearchViewController.h中:

@interface SearchViewController : UIViewController 
{
    ....
    NSMutableArray *counties;
}

....
@property (nonatomic, retain) NSMutableArray *counties;

在SearchViewController.m中:

- (void)getLocationsView
{
    [keywordField resignFirstResponder];
    SearchLocationsViewController *locationsController = 
            [[SearchLocationsViewController alloc] initWithNibName:@"SearchLocationsView" bundle:nil];
    [self.navigationController pushViewController:locationsController animated:YES];
    [locationsController setSelectedCounties:self.counties];
    [locationsController release];
}

在SearchLocationsViewController.h中:

@interface EventsSearchLocationsViewController : UIViewController 
    <UITableViewDelegate, UITableViewDataSource>
{
    ...
    NSMutableArray *selectedCounties;

}

...
@property (nonatomic, retain) NSMutableArray *selectedCounties;

在SearchLocationsViewController.m中(这里的重点是,我们正在切换表中的每个元素是否在所选县列表中处于活动状态):

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    if ([self.selectedCounties containsObject:[self.counties objectAtIndex:indexPath.row]]) {
        //we're deselcting!
        [self.selectedCounties removeObject:[self.counties objectAtIndex:indexPath.row]];
        cell.accessoryView = [[UIImageView alloc]
                              initWithImage:[UIImage imageNamed:@"red_check_inactive.png"]];
    }
    else {
        [self.selectedCounties addObject:[self.counties objectAtIndex:indexPath.row]];
        cell.accessoryView = [[UIImageView alloc]
                              initWithImage:[UIImage imageNamed:@"red_check_active.png"]];
    }
    [tableView deselectRowAtIndexPath:indexPath animated:YES];
}

[self.selectedCounties addObject.... 在那里。

现在,当我自己登录时 [self.selectedCounties class]

这是怎么发生的?我理解类束(或者我想我无论如何也理解),但这是一个显式的特定类型,它在某个点上丢失了它的子类化,从而扼杀了整个过程。我完全不明白为什么会这样。