Question

只有在NSString不使用NSASCIIStringEncoding进行编码时，我的UITableView才会出现严重的内存泄漏问题。

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

    static NSString *CellIdentifier = @"cell";
    UILabel *textLabel1;
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
        textLabel1 = [[UILabel alloc] initWithFrame:CGRectMake(105, 6, 192, 22)];

        textLabel1.tag = 1;
        textLabel1.textColor = [UIColor whiteColor];
        textLabel1.backgroundColor = [UIColor blackColor];
        textLabel1.numberOfLines = 1;
        textLabel1.adjustsFontSizeToFitWidth = NO;
        [textLabel1 setFont:[UIFont boldSystemFontOfSize:19]];
        [cell.contentView addSubview:textLabel1];
        [textLabel1 release];

    } else {
        textLabel1 = (UILabel *)[cell.contentView viewWithTag:1];
    }

    NSDictionary *tmpDict = [listOfInfo objectForKey:[NSString stringWithFormat:@"%@",indexPath.row]];

    textLabel1.text = [tmpDict objectForKey:@"name"];

    return cell;
}

-(void) readDatabase {
    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDir = [documentPaths objectAtIndex:0];
    databasePath = [documentsDir stringByAppendingPathComponent:[NSString stringWithFormat:@"%@",myDB]];
    sqlite3 *database;

    if(sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) {

        const char sqlStatement = [[NSString stringWithFormat:@"select id,name from %@ order by orderid",myTable] UTF8String];
        sqlite3_stmt *compiledStatement;
        if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) {
            while(sqlite3_step(compiledStatement) == SQLITE_ROW) {
                NSString *tmpid = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)];


                NSString *tmpname = [NSString stringWithCString:(const char *)sqlite3_column_text(compiledStatement, 1) encoding:NSUTF8StringEncoding];


                [listOfInfo setObject:[[NSMutableDictionary alloc] init] forKey:tmpid];
                [[listOfInfo objectForKey:tmpid] setObject:[NSString stringWithFormat:@"%@", tmpname] forKey:@"name"];


            }
        }
        sqlite3_finalize(compiledStatement);

        debugNSLog(@"sqlite closing");

    }
    sqlite3_close(database);

}

当我更改行

NSString *tmpname = [NSString stringWithCString:(const char *)sqlite3_column_text(compiledStatement, 1) encoding:NSUTF8StringEncoding];

到

NSString *tmpname = [NSString stringWithCString:(const char *)sqlite3_column_text(compiledStatement, 1) encoding:NSASCIIStringEncoding];

内存泄漏消失了

我试过NSString stringWithUTF8String但它仍然泄漏。我也试过了：

NSData *dtmpname = [NSData dataWithBytes:sqlite3_column_blob(compiledStatement, 1) length:sqlite3_column_bytes(compiledStatement, 1)];
NSString *tmpname = [[[NSString alloc] initWithData:dtmpname encoding:NSUTF8StringEncoding] autorelease];

问题仍然存在，当你开始滚动tableview时会发生泄漏。

我实际上尝试过其他编码，似乎只有NSASCIIStringEncoding有效（没有内存泄漏）

如果我在关闭视图之前没有滚动tableview，它根本就没有泄漏。实际上listOfInfo本身并没有泄漏，因为当我删除行时泄漏永远不会发生

textLabel1.text = [tmpDict objectForKey:@"name"];

任何想法/解决方法如何摆脱这个问题？

注意：我确实有

for (id theKey in listOfInfo) {
   [[listOfInfo objectForKey:theKey]  release];
}
[listOfInfo release];

on dealloc已经

Answer 1

程序中的泄漏实际上就在这里：

[listOfInfo setObject:[[NSMutableDictionary alloc] init] forKey:tmpid];

您正在分配字典并且永远不会释放它，因此它会泄漏。你应该写：

[listOfInfo setObject:[[[NSMutableDictionary alloc] init] autorelease] forKey:tmpid];

或

[listOfInfo setObject:[NSMutableDictionary dictionary] forKey:tmpid];

由于此字典包含您的字符串，因此字符串会与字典一起泄漏。更改为NSASCIIStringEncoding并不能解决此漏洞，它可能只是伪装它（因为字符串需要随后进行转换而Leak可能无法将其跟踪到新位置）或转换可能完全失败（如果字符串无法转换为ASCII）。

使用NSUTF8StringEncoding进行编码时，UITableView在iphone上的NSString内存泄漏

1 个答案: