刷新 uitableView 按钮单击“从 Web 服务获取数据”

Question

我正在尝试实现一种功能，即当单击 uitabbar 上的刷新按钮时，将调用返回某些数据的 Web 服务。 数据存储在SQLite DB中，然后在TableView上呈现。我的问题是，当从服务获取新数据时，数据库会更新，但更新后的记录不会立即显示在表视图中。我必须重新启动应用程序才能查看更新的记录。下面是我在点击重新加载按钮时调用的代码：

更新的代码：

-(void)get_vrns {
    NSLog(@"Refreshing...");
    NSString *delete = [NSString stringWithFormat:@"DELETE FROM VRN"];
    NSString *insert = [NSString stringWithFormat:@"INSERT INTO VRN ('VRNumber') VALUES ('%@')", @"LEC8-9436"];
    insert = @"INSERT INTO VRN ('VRNumber') VALUES ('LEC-876'); INSERT INTO VRN ('VRNumber') VALUES ('AAA-564');INSERT INTO VRN ('VRNumber') VALUES ('ABD-908'); INSERT INTO VRN ('VRNumber') VALUES ('AHF-540');";
    char *err;
    if (sqlite3_exec(db, [delete UTF8String], NULL, NULL, &err) == SQLITE_OK) {
        if (sqlite3_exec(db, [insert UTF8String], NULL, NULL, &err) != SQLITE_OK) {
            sqlite3_close(db);
            NSAssert(0, @"Could not update table");
        }
        else {
            NSLog(@"Table updated");
        }
    }
    else {
        sqlite3_close(db);
        NSAssert(0, @"Could not delete records");
    }
    [self.vrnTable reloadData];
    NSString *select = [NSString stringWithFormat:@"SELECT VRNumber FROM VRN"];
    sqlite3_stmt *statement;
    if (sqlite3_prepare_v2(db, [select UTF8String], -1, &statement, nil) == SQLITE_OK) {
        while (sqlite3_step(statement) == SQLITE_ROW) {
            char *vrn = (char *) sqlite3_column_text(statement, 0);
            NSString *vrnStr = [[NSString alloc] initWithUTF8String:vrn];
            NSString *str = [[NSString alloc] initWithFormat:@"%@", vrnStr];
            [_entries addObject:str];
        }
    }
    else {
        NSAssert1(0, @"Error: Because %s", sqlite3_errmsg(db));
    }
    NSLog(@"%@", self.entries);
}

Answer 1

想知道您在哪里存储数据以在表格视图中显示。我的意思是我们通常使用 NSArray 来存储 tableview 的数据，在 tableView：cellForRowAtIndexpath： 方法中，我们从数组中获取数据并将其放在单元格上。您是否从 sqlite 表或您正在使用的任何变量更新该数组。

更新的代码：

-(void)get_vrns {
    NSLog(@"Refreshing...");
    NSString *delete = [NSString stringWithFormat:@"DELETE FROM VRN"];
    NSString *insert = [NSString stringWithFormat:@"INSERT INTO VRN ('VRNumber') VALUES ('%@')", @"LEC8-9436"];
    insert = @"INSERT INTO VRN ('VRNumber') VALUES ('LEC-876'); INSERT INTO VRN ('VRNumber') VALUES ('AAA-564');INSERT INTO VRN ('VRNumber') VALUES ('ABD-908'); INSERT INTO VRN ('VRNumber') VALUES ('AHF-540');";
char *err;
if (sqlite3_exec(db, [delete UTF8String], NULL, NULL, &err) == SQLITE_OK) {
    if (sqlite3_exec(db, [insert UTF8String], NULL, NULL, &err) != SQLITE_OK) {
        sqlite3_close(db);
        NSAssert(0, @"Could not update table");
    }
    else {
        NSLog(@"Table updated");
    }
}
else {
    sqlite3_close(db);
    NSAssert(0, @"Could not delete records");
}
[self.entries removeAllObjects];
NSString *select = [NSString stringWithFormat:@"SELECT VRNumber FROM VRN"];
sqlite3_stmt *statement;
if (sqlite3_prepare_v2(db, [select UTF8String], -1, &statement, nil) == SQLITE_OK) {
    while (sqlite3_step(statement) == SQLITE_ROW) {
        char *vrn = (char *) sqlite3_column_text(statement, 0);
        NSString *vrnStr = [[NSString alloc] initWithUTF8String:vrn];
        NSString *str = [[NSString alloc] initWithFormat:@"%@", vrnStr];
        [_entries addObject:str];
    }
}
else {
    NSAssert1(0, @"Error: Because %s", sqlite3_errmsg(db));
}
NSLog(@"%@", self.entries);
[self.vrnTable reloadData];
}