调用 topLayoutGuide 完全中断滚动? [英] Calling topLayoutGuide breaks scrolling altogether?
问题描述
我在使用 topLayoutGuide 方法时遇到了奇怪的问题，我必须在 setAutomaticallyAdjustsScrollViewInsets: 不起作用的情况下使用它.为了缩小问题的原因，我创建了以下最小示例，它只是设置了一个用于测试的基本表视图:
I am having weird issues with the topLayoutGuide method, which I have to use in a situation where setAutomaticallyAdjustsScrollViewInsets: doesn't work. To narrow down the cause of the problem, I've created the following minimal example, which just sets up a basic table view for testing:
- 在 Xcode 中设置一个新的 iOS Single View 应用程序.
在 ViewController.m 的实现中粘贴以下代码:
- Set up a new iOS Single View application in Xcode.
Paste the following code in ViewController.m's implementation:
@implementation ViewController
- (void)loadView
{
[self setTableView:[[UITableView alloc] initWithFrame:CGRectZero style:UITableViewStylePlain]];
}
- (void)viewDidLoad
{
[super viewDidLoad];
[self setAutomaticallyAdjustsScrollViewInsets:NO]; // [*]
}
- (void)viewDidLayoutSubviews
{
UITableView *tableView = [self tableView];
UIEdgeInsets insets = [tableView contentInset];
// insets.top = [[self topLayoutGuide] length]; // [1]
// insets.top = 100; // [2]
[tableView setContentInset:insets];
[tableView setScrollIndicatorInsets:insets];
}
#pragma mark - Table view data source
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 100;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
[[cell textLabel] setText:[NSString stringWithFormat:@"%d", [indexPath row]]];
return cell;
}
@end
我遇到的问题是:
如果我取消注释标有
[1]的行，将应用正确的插图，但滚动表格视图不再有效.当我尝试滚动时，在我松开手指后，表格会弹回到初始滚动位置.此行为也由对[self topLayoutGuide]的简单调用触发，无需将结果分配给任何内容.
If I uncomment the line marked with
[1], the correct inset is applied, but scrolling the table view no longer works. When I try to scroll, the table just bounces back to the initial scroll position after I release my finger. This behaviour is also triggered by a plain call to[self topLayoutGuide], without assigning the result to anything.
如果我取消注释行 [2] 而不是 [1]，滚动工作.也应用了 100 pt 的插图.但现在初始滚动位置会自动调整，使内容覆盖在状态栏下方.
If I uncomment line [2] instead of [1], scrolling works. The inset of 100 pt is applied as well. But now the initial scrolling position is automatically adjusted so that the content underlaps the status bar.
([*]: 这真的只是与包含导航控制器结合做任何事情.我在这个例子中似乎没有什么不同，但我想禁用任何自动行为只是为了确定.)
([*]: This really only seems to do anything in combination with a containing navigation controller. I doesn't seem to make a difference in this example, but I want to disable any automatic behaviour just to be sure.)
有什么明显的我做错了吗?我真的很茫然.
Is there anything obvious I'm doing wrong? I'm really at a loss here.
推荐答案
这绝对是 iOS 7 中的一个错误(在 7.1 中似乎没有修复)但似乎只影响 UITableViewControllers.我切换到使用带有嵌入式 UITableView 的 UIViewController，因为我没有使用静态单元格并且不需要任何 UITableViewController 给你.
This is definitely a bug in iOS 7 (doesn't appear to be fixed in 7.1) but seems to only affect UITableViewControllers. I switched over to using a UIViewController with an embedded UITableView since I am not using static cells and don't need any of the 'magic' that a UITableViewController gives you.
一旦我手动连接了 UITableViewDataSource 和 UITableViewDelegate，我就可以开始使用 self.topLayoutGuide 而不会弄乱 tableView 的 contentSize.
Once I wired up the UITableViewDataSource and UITableViewDelegate manually I was able to start using self.topLayoutGuide without messing up the tableView's contentSize.
在 Apple 修复错误之前，这对我来说是一个可以接受的解决方法.
This was an acceptable workaround for me until Apple fixes the bug.
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