坏的UITableViewCell性能自动版式 [英] UITableViewCell bad performance with AutoLayout

问题描述

我有点卡住了这一个...任何帮助是非常AP preciated。我已经花了很多时间调试此。

I'm somewhat stuck with this one… any help is very appreciated. I've already spent lots of time debugging this.

我已经有了的UITableView 与 NSFetchedResultsController 提供的数据源。在一个单独的视图控制器我使用插入新记录到CoreData [NSEntityDescription insertNewObjectForEntityForName：inManagedObjectContext：] ，表示被管理对象上下文并关闭该控制器。很标准的东西。

I've got UITableView with data source provided by NSFetchedResultsController. In a separate view controller I insert new records to the CoreData using [NSEntityDescription insertNewObjectForEntityForName:inManagedObjectContext:], save the managed object context and dismiss that controller. Very standard stuff.

在管理对象方面的变化，然后由收 NSFetchedResultsController ：

The changes in managed object context are then received by NSFetchedResultsController:

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
        [self.tableView beginUpdates];
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
        [self.tableView endUpdates];
}

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
    switch (type) {
        case NSFetchedResultsChangeInsert:
            [self.tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationNone];

            break;

        case NSFetchedResultsChangeDelete:
            [self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationNone];

            break;

        case NSFetchedResultsChangeUpdate:
            [self.tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationNone];

            break;

        case NSFetchedResultsChangeMove:
            [self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationNone];
            [self.tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationNone];

            break;
    }
}

这是问题出现的地方 - 它的时间太长（约3-4秒在iPhone 4）做到这一点。而且好像时间都花在计算布局单元格。

And this is where the problem appears — it takes too long(about 3-4 seconds on an iPhone 4) to do that. And it seems like the time is spent calculating layout for the cells.

我从小区（包括自定义子类）剥离一切，只用的UILabel ，但没有改变离开它。然后，我已经改变了细胞基本（或自定义以外的任何东西）的风格，问题就消失了 - 新的细胞在瞬间补充

I've stripped everything from the cell(including custom subclass) and left it with just UILabel, but nothing changed. Then I've changed the style of the cell to Basic(or anything except Custom) and the problem disappeared — new cells are added instantaneously.

我已经翻了一番检查和 NSFetchedResultsControllerDelegate 回调称为一次。如果我不理会他们，做 [UITableView的reloadSections：withRowAnimation：] ，没有什么变化 - 它仍然是非常缓慢的。

I've doubled checked and NSFetchedResultsControllerDelegate callbacks are called only once. If I ignore them and do [UITableView reloadSections:withRowAnimation:], nothing changes — it is still very slow.

在我看来，像自动布局是默认单元格样式，这使得它们非常快禁用。但是，如果是这样的话 - 为什么做一切能够快速加载，当我推的UITableViewController

It seems to me like Auto Layout is disabled for the default cell styles, which makes them very fast. But if that is the case — why does everything loads quickly when I push the UITableViewController?

下面对于此问题的呼叫跟踪：

Here's the call trace for that problem:

所以，问题是 - 什么是怎么回事？为什么细胞被渲染得很慢？

So the question is — what is going on here? Why are cells being rendered so slowly?

更新1

我已经建立了一个非常简单的演示程序，说明我有这个问题。这里的源 - <一个href=\"https://github.com/antstorm/UITableViewCellPerformanceProblem\">https://github.com/antstorm/UITableViewCellPerformanceProblem

I've built a very simple demo app that illustrates the problem I'm having. here's the source — https://github.com/antstorm/UITableViewCellPerformanceProblem

尝试增加至少细胞满屏感受到性能问题。

Try adding at least a screenful of cells to feel the performance problems.

另外请注意，直接添加行（现在插入！按钮），没有造成任何进展缓慢。

Also note that adding a row directly ("Insert now!" button) is not causing any slowness.

推荐答案

好吧，我终于绕不牺牲动漫这个问题了。我的解决方法是实施的UITableViewCell 的与自动版式残疾人单独护理文件的界面。这需要一点点更长的加载时间，你需要的位置子视图自己。

Ok, I finally got around this problem without sacrificing animation. My solution is to implement UITableViewCell's interface in a separate Nib file with AutoLayout disabled. It takes a little bit longer to load and you need to positions subviews yourself.

这里的code，使之成为可能：

Here's the code to make it possible:

- (void)viewDidLoad {
    [super viewDidLoad];

    ...        

    UINib *rowCellNib = [UINib nibWithNibName:@"RowCell" bundle:nil];
    [self.tableView registerNib:rowCellNib forCellReuseIdentifier:@"ROW_CELL"];
}

当然，你需要用你的手机的视图RowCell.nib文件。

Of course you'll need a RowCell.nib file with your cell's view.

虽然没有解决原来的问题（这显然似乎是一个错误给我），我使用的这一个。

While there's no solution to the original problem(which clearly seems a bug to me), I'm using this one.

这篇关于坏的UITableViewCell性能自动版式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！