cocoa - NSMutableDictionary 内存问题，导致 NSCFDictionary 内存泄漏

Question

请帮我解决以下问题:

- (NSDictionary *)getGamesList
{
    NSMutableDictionary *gamesDictionary = [[NSMutableDictionary dictionary] retain];
// I was trying to change this on the commented code below, but did have no effect
//    NSMutableDictionary *gamesDictionary = [[NSMutableDictionary alloc] init];
//    [gamesDictionary retain];
    while (sqlite3_step(statement) == SQLITE_ROW)
    {
        NSString *key = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, 1)];
        NSArray *gameDate = [key componentsSeparatedByString:@" "];
        NSNumber *_id = [[NSNumber alloc] initWithInt:sqlite3_column_int(statement, 0)];
        NSString *date_time = [NSString stringWithFormat:@"%@, %@",[gameDate objectAtIndex:0],[gameDate objectAtIndex:2]];
        if (![gamesDictionary valueForKey:date_time]) [gamesDictionary setValue:[NSMutableArray array] forKey:date_time];
        [[gamesDictionary valueForKey:date_time] addObject:[[_id copy] autorelease]];
        [_id release];
    }
    sqlite3_reset(statement);
    return gamesDictionary;
}

泄漏从另一个类的另一个方法开始，在那里调用 getGamesList 方法，如下所示:

NSMutableDictionary *gamesDictionary;
gamesDictionary = [[NSMutableDictionary dictionaryWithDictionary:[appDelegate getGamesList]] retain];

之后，字符串中有很多指向 NSCFArray 的泄漏:

NSArray *keys = [[NSArray arrayWithArray:[gamesDictionary allKeys]] retain]; 

在此方法中:

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    NSArray *keys = [[NSArray arrayWithArray:[gamesDictionary allKeys]] retain];
    if ([keys count] != 0)    return [[keys objectAtIndex:section] uppercaseString];
    return @"";
}

我假设这些东西是相互关联的，但我仍然无法理解所有的内存管理技巧。非常感谢!

Answer 1

多年来没有使用 Cocoa(这就是为什么我不能告诉你确切的答案:/)。但我猜你的问题是你系统地使用 retain在你的物体上。

由于对象引用计数永远不会达到 0，因此所有字典都保留在内存中并且不会释放。

尝试删除retain上[NSArray arrayWithArray]和[NSMutableDictionary dictionaryWithDictionary

http://en.wikibooks.org/wiki/Programming_Mac_OS_X_with_Cocoa_for_beginners/Some_Cocoa_essential_principles#Retain_and_Release