调用cellForRowAtIndexPath：是否实用？ [英] Is calling cellForRowAtIndexPath: ever practical?

问题描述

直接实现 UITableViewDelegate 和 UITableViewDataSource 时，我见过很多许多开发人员将 cellForRowAtIndexPath：调用为：

I've seen many many developers when implementing a UITableViewDelegate and UITableViewDataSource directly call cellForRowAtIndexPath: to either:

1）检索单元格以获取存储在$ b内的模型元素$ b单元格：

1) Retrieve the cell to grab a model element that they stored within the cell:

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
    MyCell *cell = (MyCell *)[tableView cellForRowAtIndexPath:indexPath];
    int secretCode = cell.secretCode;
    LaunchMissileViewController *vc = [[LaunchMissileViewController alloc] initWithSecretCode:secretCode];
    [self.navigationController pushViewController:vc];
}

2）尝试设置单元格样式（这有明显的问题，但似乎非常常见）：

2) Attempt to style the cell (this has clear problems, but seems very common):

MyCell *cell = (MyCell *)[self cellForRowAtIndexPath:indexPath];
// or [tableView cellForRowAtIndexPat:indexPath];
cell.backgroundColor = [UIColor greenColor];

制作只有框架永远调用 cellForRowAtIndexPath：？或者是否有一个人可能自己称之为的实际原因？

Is it safe to make the blanket statement that "only the framework should ever call cellForRowAtIndexPath:"? Or is there a practical reason one might ever call it themselves?

推荐答案

就我个人而言，我认为没有好的案例可以直接在数据源上直接调用 tableView：cellForRowAtIndexPath：。

Personally I don't think there are ever good cases to directly call tableView:cellForRowAtIndexPath: directly on the data source.

对于情况＃1，它只是编码错误。单元格永远不应包含数据。数据源应具有数据，因此从实际数据源而不是单元格获取数据。

For case #1 it is simply bad coding. The cell should never contain the data. The data source should have the data so get the data from the actual data source, not the cell.

对于情况＃2，您只需要更新可见单元格。为此，您可以使用 UITableView cellForRowAtIndexPath：方法。无需为单元格调用数据源。

For case #2 you would only ever need to update a visible cell. And for this you can use the UITableView cellForRowAtIndexPath: method. No need to call the data source for the cell.

我尝试永远不要说从不但它应该是一个非常罕见的情况，你真的需要得到通过调用数据源方法来获取单元格。

I try never to say "never" but it should be an extremely rare case where you have a real need to get the cell by calling the data source method.

这篇关于调用cellForRowAtIndexPath：是否实用？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！