EXEC_BAD_ACCESS при вызове метода SQLLite

sqlite3_stmt *stmt;

    NSString *selectQuery =[NSString stringWithFormat:@"select * from myaccount"];

    NSMutableArray *fl =[[NSMutableArray alloc]init];
    NSString *sname;
    NSString *myMobNo;
    NSMutableString *str = [[NSMutableString alloc]init];

    if (sqlite3_prepare_v2(db, [selectQuery UTF8String], -1, &stmt, nil) == SQLITE_OK) {
        while (sqlite3_step(stmt) == SQLITE_ROW) {

            sname = [NSString stringWithUTF8String:(char *)sqlite3_column_text(stmt, 1)];
            myMobNo = [NSString stringWithUTF8String:(char *)sqlite3_column_text(stmt, 4)];
            [str appendString:[NSString stringWithFormat:@"%@!%@",sname,myMobNo]];

            [fl addObject:str];

        }
    }

    sqlite3_finalize(stmt);

    return fl;

Я использую Objective C с SQL Lite в моем проекте. Когда я вызываю метод выше, я получаю ошибку как EXC_BAD_ACCESS при условии If. Что не так с моим кодом. Любая помощь будет оценена заранее.

  0x0003c099 -[DBModel getCName] + 112
1   Kinkey  0x0001d623 -[ChatViewController viewDidLoad] + 302
2   0x34dae579 <redacted> + 364
3   0x34e031f7 <redacted> + 26
4   0x34e0313d <redacted> + 28
5   0x34e03021 <redacted> + 32
6   0x34e02f4d <redacted> + 272
7   0x34e02699 <redacted> + 64
8   0x34e02581 <redacted> + 324
9   0x34df0b5b <redacted> + 858
10  0x34df07fb <redacted> + 38
11  0x0004cd33 -[ChatView tableView:didSelectRowAtIndexPath:] + 970
12  0x34e5131d <redacted> + 876
13  0x34ed3da9 <redacted> + 156
14  0x3388f657 <redacted> + 450
15  0x32f55857 <redacted> + 14
16  0x32f55503 <redacted> + 274
17  0x32f54177 <redacted> + 1230
18  0x32ec723d CFRunLoopRunSpecific + 356
19  0x32ec70c9 CFRunLoopRunInMode + 104
20  0x36aa533b GSEventRunModal + 74
21  0x34de32b9 UIApplicationMain + 1120
22  0x00002a31 main + 108
23  0x000024cc start + 40



NSMutableArray *Details = [[DBModel database]getCName];
    NSArray *array = [[Details objectAtIndex:0] componentsSeparatedByString:@"!"];
    acName = [array objectAtIndex:0];
    acMobileNo = [array objectAtIndex:1];

if ((char *)sqlite3_column_text(stmt4, 1)!= nil) {
        sname = [NSString stringWithUTF8String:(char *)sqlite3_column_text(stmt4, 1)];
        }