ios - ( Objective-C )在 sqlite 数据库中保存更改

Question

我正在为我的学校项目创建一个应用程序，它必须将数据写入我的 sqlite 数据库。只要应用程序处于事件状态，它就可以工作，但一旦应用程序关闭，我添加的数据就会消失，当我想读取这些数据时，这将无法正常工作。我包括了我的 loadData 和 saveData 方法。两个函数中的两个数据库路径相同，所以我并不是在别处写数据。我真的找不到解决方案或问题。我什至在我的输出中得到插入成功，所以插入成功。

- (void) saveData:(id)sender{
    NSString *sqldb = [[NSBundle mainBundle] pathForResource:@"PXLate" ofType:@"sqlite3"];
    sqlite3_stmt *stmt;
    NSString *queryInsert = @"INSERT INTO assignments (name, lesson, dueDate, notification, start, at) VALUES ('abc','abc', 'abc', 1, 'abc', 'abc')";
    NSLog(@"%@",sqldb);

    NSLog(@"%@",queryInsert);
    if(sqlite3_open([sqldb UTF8String], &_PXLate) == SQLITE_OK)
    {
        sqlite3_prepare_v2(_PXLate, [queryInsert UTF8String], -1, &stmt, NULL);

        if(sqlite3_step(stmt)==SQLITE_DONE)
        {
            NSLog(@"insert success");
        }
        else
        {
            NSLog(@"insert un success");
            NSAssert1(0, @"Error: failed to prepare statement with message '%s'.", sqlite3_errmsg(_PXLate));
        }

        int success=sqlite3_step(stmt);

        if (success == SQLITE_ERROR)
        {
            NSAssert1(0, @"Error: failed to insert into the database with message '%s'.", sqlite3_errmsg(_PXLate));
            //[_PXLate save:&error];

        }        sqlite3_finalize(stmt);
    }
    sqlite3_close(_PXLate);
}

和我的loadData函数

- (void) loadData:(id)sender
{
     //path for database
        NSString *sqldb = [[NSBundle mainBundle] pathForResource:@"PXLate" ofType:@"sqlite3"];
    //check if present
    NSFileManager*fm=[NSFileManager defaultManager];
        NSLog(@"path: %@", sqldb);

    const char *dbpath = [sqldb UTF8String];
    sqlite3_stmt    *statement;

    if (sqlite3_open(dbpath, &_PXLate) == SQLITE_OK)
    {
        NSString *querySQL = [NSString stringWithFormat: @"SELECT * FROM assignments WHERE name='abc'", _label.text];
        const char *query_stmt = [querySQL UTF8String];
        NSLog(@"name");
        NSLog(querySQL);
        int response = sqlite3_prepare_v2(_PXLate, query_stmt, -1, &statement, NULL);
        NSLog(@"response %d", response);

        if (response == SQLITE_OK)
        {
            NSLog(@"name");
            if (sqlite3_step(statement) == SQLITE_ROW)
            {
                NSString *namefield = [[NSString alloc]
                                          initWithUTF8String:
                                          (const char *) sqlite3_column_text(
                                                                             statement, 0)];
                NSLog(@"name:%@", namefield);
                _label.text = namefield;
            } else {
                _label.text = @"Match not found";

            }
            sqlite3_finalize(statement);
        }
        sqlite3_close(_PXLate);
    }
}

Answer 1

您必须将 sqlite 复制到文档目录，然后使用它。示例:

self.databaseName = @"databasename.sqlite";

// Get the path to the documents directory and append the databaseName
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDir = [documentPaths objectAtIndex:0];

self.databasePath = [[NSString alloc]init];
self.databasePath = [documentsDir stringByAppendingPathComponent:self.databaseName];
[self checkAndCreateDatabase];

创建方法:

-(void)checkAndCreateDatabase 
{
   NSFileManager *fileManager = [NSFileManager defaultManager];
   NSString *databasePathFromApp = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:self.databaseName];
   [fileManager copyItemAtPath:databasePathFromApp toPath:self.databasePath error:nil];
}