Question

我的应用程序中有3个内存泄漏，我找不到如何修复它。我是xcode和Objective c的新手。这是我的代码：

if(sqlite3_prepare_v2( [[DatabaseController sharedDatabaseController] getDb], sqlQueryConverted, -1, &dbStatement, NULL)==SQLITE_OK){

        //Run the query
        while ( sqlite3_step(dbStatement) == SQLITE_ROW ) 
        {    


            const char *name = (const char *)sqlite3_column_text(dbStatement, 0);
            int courseId = sqlite3_column_int(dbStatement, 1);
            const char *location = (const char *)sqlite3_column_text(dbStatement, 2);
            const char *date = (const char *)sqlite3_column_text(dbStatement, 3);

            //Convert the returnedElement char to string
            nameConverted = [[NSString alloc] initWithUTF8String:name];
            locationConverted = [[NSString alloc] initWithUTF8String:location];
            dateConverted = [[NSString alloc] initWithUTF8String:date];

            Course *course = [[[Course alloc]initWithName:nameConverted _id:courseId location:locationConverted courseDate:dateConverted] autorelease];

            //Add the course to the to a temporary list to remove duplicated items            
            [tempResults addObject:course];

        }  
        [nameConverted release];
        [locationConverted release];
        [dateConverted release];
    }

我也尝试过自动退款。此代码用于过滤搜索并重新加载搜索显示表。如果我将release行放在while语句中，如果我键入2个字母，应用程序将崩溃。我怎么能解决这个问题？

感谢。

编辑：我一直在这个问题上来回走动，没有运气。我得出的结论是，仪器出了问题，因为它仍然显示内存泄漏。这是今天的代码，我认为应该解决问题：

NSString *nameConverted = [[NSString alloc] initWithUTF8String:name];
            NSString *locationConverted = [[NSString alloc] initWithUTF8String:location];
            NSString *dateConverted = [[NSString alloc] initWithUTF8String:date];

            Course *course = [[[Course alloc]initWithName:nameConverted _id:courseId location:locationConverted courseDate:dateConverted] autorelease];

            //Add the course to the to a temporary list to remove duplicated items            
            [tempResults addObject:course];
            course = nil;
            [course release];
            [nameConverted release];
            nameConverted = nil;
            [locationConverted release];
            locationConverted = nil;
            [dateConverted release];
            dateConverted = nil;
            NSLog(@"course retain count %i",[course retainCount]);
            NSLog(@"name coverted retain count %i",[nameConverted retainCount]);
            NSLog(@"location coverted retain count %i",[locationConverted retainCount]);
            NSLog(@"date coverted retain count %i",[dateConverted retainCount]);

日志告诉我retainCount = 0;所以我不明白为什么会有内存泄漏。你能给我一些建议吗？

再次感谢。

Answer 1

你在每个循环都漏掉了。你只发布了3个持续的NSString。每当你为你的3个变量（nameConverted，locationConverted，dateConverted）重新分配一个新的NSString时，你就会失去对它们所指向的NSString对象的引用。这意味着内存泄漏。当你离开While循环时，你只释放最后的3个。

Answer 2

您在每次循环时创建一个内存块，然后只释放一次。因此，如果while循环运行超过10次，则每个字符串的保留计数为10，但只释放一次。

要修复，请将3个版本放入while循环中，如下所示：

if(sqlite3_prepare_v2( [[DatabaseController sharedDatabaseController] getDb], sqlQueryConverted, -1, &dbStatement, NULL)==SQLITE_OK){

        //Run the query
        while ( sqlite3_step(dbStatement) == SQLITE_ROW ) 
        {    


            const char *name = (const char *)sqlite3_column_text(dbStatement, 0);
            int courseId = sqlite3_column_int(dbStatement, 1);
            const char *location = (const char *)sqlite3_column_text(dbStatement, 2);
            const char *date = (const char *)sqlite3_column_text(dbStatement, 3);

            //Convert the returnedElement char to string
            nameConverted = [[NSString alloc] initWithUTF8String:name];
            locationConverted = [[NSString alloc] initWithUTF8String:location];
            dateConverted = [[NSString alloc] initWithUTF8String:date];

            Course *course = [[[Course alloc]initWithName:nameConverted _id:courseId location:locationConverted courseDate:dateConverted] autorelease];

            //Add the course to the to a temporary list to remove duplicated items            
            [tempResults addObject:course];

        [nameConverted release];
        [locationConverted release];
        [dateConverted release];

        }  

    }

Answer 3

您是否尝试过使用：

nameConverted = [[NSString initWithUTF8String:name] autorelease];
locationConverted = [[NSString initWithUTF8String:location] autorelease];
dateConverted = [[NSString initWithUTF8String:date] autorelease];

并删除循环外的版本？也不要自动移动课程对象，在将其添加到tempResults后将其释放。

Answer 4

这就是你应该这样做的方式。

NSString *nameConverted = [[NSString alloc] initWithUTF8String:name];
NSString *locationConverted = [[NSString alloc] initWithUTF8String:location];
NSString *dateConverted = [[NSString alloc] initWithUTF8String:date];

Course *course = [[Course alloc] initWithName:nameConverted _id:courseId location:locationConverted courseDate:dateConverted];
[tempResults addObject:course];
[course release];

[dateConverted release];
[locationConverted release];
[nameConverted release];

麻烦修复内存泄漏iphone

4 个答案: