objective-c - 为什么我收到 : "mutating method sent to immutable object" when trying remove from MutableArray?

Question

我不明白为什么我在这段代码中收到“发送到不可变对象(immutable对象)的变异方法”。该数组必须以某种方式是不可变的，但我不知道为什么。

界面:

    @interface SectionsViewController : UIViewController<UITableViewDelegate, UITableViewDataSource, UISearchBarDelegate> {

    UITableView *table;
    UISearchBar *search;
    NSMutableDictionary *names;
    NSMutableArray *keys;

}
@property (nonatomic, retain) IBOutlet UITableView *table;
@property (nonatomic, retain) IBOutlet UISearchBar *search;
@property (nonatomic, retain) NSDictionary *allNames;
@property (nonatomic, retain) NSMutableDictionary *names;
@property (nonatomic, retain) NSMutableArray *keys;

-(void) resetSearch;
-(void) handleSearchForTerm:(NSString *)searchTerm;

@end

请注意，names 是一个 MutableDictionary。

下面一行抛出异常

[array removeObjectsInArray:toRemove];

这里是完整上下文中的方法:

-(void)handleSearchForTerm:(NSString *)searchTerm
{
    NSMutableArray *sectionsToRemove = [[NSMutableArray alloc] init];
    for(NSString *key in self.keys)
    {
        NSMutableArray *array = [names valueForKey:key];
        NSMutableArray *toRemove = [[NSMutableArray alloc] init];

        for(NSString *name in array)
        {
            if([name rangeOfString:searchTerm
                           options:NSCaseInsensitiveSearch].location == NSNotFound)
                [toRemove addObject:name];
        }
        if([array count] == [toRemove count])
            [sectionsToRemove addObject:key];

        [array removeObjectsInArray:toRemove];
        [toRemove release];
    }
    [self.keys removeObjectsInArray:sectionsToRemove];
    [sectionsToRemove release];
    [table reloadData];
}

我正在根据此 [names valueForKey:key]; 的结果分配数组；数组的类型为“MutableArray”我缺少什么？

谢谢!

Answer 1

valueForKey: 返回一个 NSArray。将其发送到 NSMutableArray 并不重要。

您可以将结果转换为 (NSMutableArray *)，但我个人偏好是获取副本:

NSMutableArray *array = [[[names valueForKey:key] mutableCopy] autorelease];