Question

每个人都

我正在使用以下代码将存储在数据库中的数据加载到表视图中，但是当我重新启动应用程序时它会被删除

InsertRecord是类insertUpdateDelete

的实例

+ (void) getInitialDataToDisplay:(NSString *)dbPath 
{


    iICS_testAppDelegate *appDelegate = (iICS_testAppDelegate *)[[UIApplication sharedApplication] delegate];

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

        const char *sql = "select * from tbl_Users";
        sqlite3_stmt *selectstmt;
        if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {

            while(sqlite3_step(selectstmt) == SQLITE_ROW) {

                NSInteger primaryKey = sqlite3_column_int(selectstmt, 0);
                insertUpdateDelete *InsertRecord = [[insertUpdateDelete alloc] initWithPrimaryKey:primaryKey];

                InsertRecord.strFirstName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 1)];
                InsertRecord.strMiddleName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 2)];
                [appDelegate.arrObjects addObject:InsertRecord];
                [InsertRecord release];
            }
        }
    }
    else
    {
        sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory.
    }
    NSLog(@"arrObjects----%@",appDelegate.arrObjects);
}

应用程序崩溃在以下行

 InsertRecord.strFirstName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 1)];

崩溃日志是 - 由于未捕获的异常'NSInvalidArgumentException'终止应用程序，原因：' * + [NSString stringWithUTF8String：]：NULL cString'

Answer 1

您需要检查数据库中的空数据;

// load char in temporary variable
char *tempChar = sqlite3_column_text(selectstmt, 1);

if(tempChar == null)  // test for null
    InsertRecord.strFirstName = nil;
else
    InsertRecord.strFirstName = [NSString stringWithUTF8String:tempChar];

// go to the next field in the database
tempChar = sqlite3_column_text(selectstmt, 2);

// do the same type of test

Answer 2

测试sqlite3_column_text(selectstmt, 1)是否返回有效字符串。

Answer 3

(char *)sqlite3_column_text(selectstmt, 1) should be given nil (null) value.

因此，从数据库获取数据时添加验证。

像，

if ((char *)sqlite3_column_text(selectstmt, 1) != nil)
{
    InsertRecord.strFirstName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 1)];

}
else
{
    InsertRecord.strFirstName = @"";
}

将数据库中存储的数据加载到表视图中时出现问题

3 个答案: