SQLite EXC_BAD_ACCESS

Question

我在sqlite3_prepare之後立即得到EXC_BAD_ACCESS錯誤。任何想法將不勝感激？請注意，我正在使用4個sql語句循環訪問數據庫。第一次迭代總是正常工作，第二次迭代拋出錯誤。

更新：第一條SQL語句的工作原理是因爲它沒有返回任何值。

-(NSMutableArray *) categoryList{ 
    categories = [NSMutableArray array]; 
    const char *sql; 

    for (int i = 0; i < 4; i++){ 
     @try { 
      NSFileManager *fileMgr = [NSFileManager defaultManager]; 
      NSString *dbPath = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:@"webdemo.db"]; 
      BOOL success = [fileMgr fileExistsAtPath:dbPath]; 
      if(!success) 
      { 
       NSLog(@"Cannot locate database file '%@'.", dbPath); 
      } 
      if(!(sqlite3_open([dbPath UTF8String], &db) == SQLITE_OK)) 
      { 
       NSLog(@"An error has occured: %@", sqlite3_errmsg(db)); 
      } 

      //queries for category captions and category images 
      //get images from category attach first 
      //take high res images first 
      switch (i){ 
       case 0: //high res image in category attach 
        sql = "SELECT DISTINCT a.CategoryCaption1, b.LocationHigh FROM CategoryAdvance a JOIN CategoryAttach b ON a.CategoryText1 = b.CategoryText1 WHERE b.LocationHigh IS NOT NULL"; 
        break; 
       case 1: //low res image in category attach 
        sql = "SELECT DISTINCT a.CategoryCaption1, b.Location FROM CategoryAdvance a JOIN CategoryAttach b ON a.CategoryText1 = b.CategoryText1 WHERE b.LocationHigh IS NULL AND b.Location IS NOT NULL"; 
        break; 
       case 2: //high res image in category advance 
        sql = "SELECT DISTINCT CategoryCaption1, CategoryHIRESPicPath FROM CategoryAdvance where CategoryText1 NOT IN (SELECT CategoryText1 from CategoryAttach where LocationHigh IS NOT NULL or Location IS NOT NULL) AND CategoryHIRESPicPath IS NOT NULL"; 
        break; 
       case 3: //low res image in category advance 
        sql = "SELECT DISTINCT CategoryCaption1, CategoryPicPath FROM CategoryAdvance where CategoryText1 NOT IN (SELECT CategoryText1 from CategoryAttach where LocationHigh IS NOT NULL or Location IS NOT NULL) AND CategoryHIRESPicPath IS NOT NULL"; 
        break; 
      } 

      sqlite3_stmt *sqlStatement; 
      if(sqlite3_prepare(db, sql, -1, &sqlStatement, NULL) != SQLITE_OK) 
      { 
       NSLog(@"Problem with prepare statement: %@", sqlite3_errmsg(db)); 
      }else{ 

       while (sqlite3_step(sqlStatement)==SQLITE_ROW) { 
        Category *category = [[Category alloc] init]; 
        category.caption = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,0)]; 
        category.imageName = @"AppIcon-retina.png"; //[NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,1)]; 
        [category parseImageName]; 
        [categories addObject:category]; 
       } 
      } 

      sqlite3_finalize(sqlStatement); 

     } 
     @catch (NSException *exception) { 
      NSLog(@"Problem with prepare statement: %@", sqlite3_errmsg(db)); 
     } 
     @finally { 
      //sqlite3_finalize(sqlStatement); 
      sqlite3_close(db); 
     } 
    } 


    //delete duplicate categories 

    //order categories alphabetically 


    return categories; 
} 

Answer 1

我認爲問題是在finalize語句中，如果語句沒有準備好，那麼它也會調用finalize方法。

檢查與重新編寫代碼：

-(NSMutableArray *) categoryList 
{ 
    categories = [NSMutableArray array]; 
    const char *sql; 
    @try 
    { 
     NSFileManager *fileMgr = [NSFileManager defaultManager]; 
     NSString *dbPath = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:@"webdemo.db"]; 
     BOOL success = [fileMgr fileExistsAtPath:dbPath]; 
     if(!success) 
     { 
      NSLog(@"Cannot locate database file '%@'.", dbPath); 
     } 
     if(!(sqlite3_open([dbPath UTF8String], &db) == SQLITE_OK)) 
     { 
      NSLog(@"An error has occurred"); 
     } 
     for (int i = 0; i < 4; i++) 
     { 
     switch (i){ 
      case 0: //high res image in category attach 
       sql = "SELECT DISTINCT a.CategoryCaption1, b.LocationHigh FROM CategoryAdvance a JOIN CategoryAttach b ON a.CategoryText1 = b.CategoryText1 WHERE b.LocationHigh IS NOT NULL"; 
       break; 
      case 1: //low res image in category attach 
       sql = "SELECT DISTINCT a.CategoryCaption1, b.Location FROM CategoryAdvance a JOIN CategoryAttach b ON a.CategoryText1 = b.CategoryText1 WHERE b.LocationHigh IS NULL AND b.Location IS NOT NULL"; 
       break; 
      case 2: //high res image in category advance 
       sql = "SELECT DISTINCT CategoryCaption1, CategoryHIRESPicPath FROM CategoryAdvance where CategoryText1 NOT IN (SELECT CategoryText1 from CategoryAttach where LocationHigh IS NOT NULL or Location IS NOT NULL) AND CategoryHIRESPicPath IS NOT NULL"; 
       break; 
      case 3: //low res image in category advance 
       sql = "SELECT DISTINCT CategoryCaption1, CategoryPicPath FROM CategoryAdvance where CategoryText1 NOT IN (SELECT CategoryText1 from CategoryAttach where LocationHigh IS NOT NULL or Location IS NOT NULL) AND CategoryHIRESPicPath IS NOT NULL"; 
       break; 
     } 

     sqlite3_stmt *sqlStatement; 
     if(sqlite3_prepare(db, sql, -1, &sqlStatement, NULL) != SQLITE_OK) 
     { 
      NSLog(@"Problem with prepare statement"); 
     } 
     else 
     { 

      while (sqlite3_step(sqlStatement)==SQLITE_ROW) 
      { 
       Category *category = [[Category alloc] init]; 
       category.caption = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,0)]; 
       category.imageName = @"AppIcon-retina.png"; //[NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,1)]; 
       [category parseImageName]; 
       [categories addObject:category]; 
      } 
      sqlite3_finalize(sqlStatement); 
     } 
    } 
    } 
    @catch (NSException *exception) 
    { 
    NSLog(@"Problem with prepare statement"); 
    } 
    @finally 
    { 
    sqlite3_close(db); 
    } 
    return categories; 
}