核心数据：UITableView与多个NSFetchedResultControllers [英] Core Data: UITableView with multiple NSFetchedResultControllers

问题描述

我想做的是很简单。在我的UITableViewController，我想从多个NSFetchedResultController（我有多个实体在我的数据模型中）加载数据，并将每个数据放入表视图中的不同部分。因此，例如，来自第一个NSFetchedResultController的所有获取的项目将在UITableView中的第0部分，从另一个获取的项目进入第1部分等。

What I want to do is pretty simple. In my UITableViewController, I want to load data from multiple NSFetchedResultControllers (I have multiple entities in my data model) and put data from each one into a different section in the table view. So for example, all the fetched items from the first NSFetchedResultController would go in section 0 in the UITableView, the fetched items from the other one goes into section 1, etc.

Core Data模板项目不会演示如何执行此操作。一切（主要是索引路径）被编码，而不考虑节（在默认模板中没有节），一切都从一个NSFetchedResultController。

The Core Data template project doesn't demonstrate how to do this. Everything (mainly the index paths) is coded without taking sections into account (there are no sections in the default template) and everything is taken from a single NSFetchedResultController. Are there any example projects or documentation that demonstrates doing this?

感谢

推荐答案

假设您的标题中有以下内容（下面的代码将稍微有点草率，我的歉意）：

Assume for a moment the following in your header (code below will be slightly sloppy, my apologies):

NSFetchedResultsController *fetchedResultsController1; // first section data
NSFetchedResultsController *fetchedResultsController2; // second section data

让表知道你想要两个节：

Let the table know you want to have 2 sections:

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 2; // you wanted 2 sections
}

Give it the section titles:

- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView {
    return [NSArray arrayWithObjects:@"First section title", @"Second section title", nil];
}

让表知道每个部分有多少行：

Let the table know how many rows there are per sections:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    if (section == 0) {
        return [[fetchedResultsController1 fetchedObjects] count];
    } else if (section == 1) {
        return [[fetchedResultsController2 fetchedObjects] count];
    }

    return 0;
}

建立储存格：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    ... // table cell dequeue or creation, boilerplate stuff

    // customize the cell
    if (indexPath.section == 0) {
        // get the managed object from fetchedResultsController1
        // customize the cell based on the data
    } else if (indexPath.section == 1) {
        // get the managed object from fetchedResultsController2
        // customize the cell based on the data
    }

    return cell;
}

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