为什么UIViewController扩展到UINavigationBar，而UITableViewController没有?

I have UITabbarController with UINavigationController in it. I have a subclass of UIView that I assign as the view of UIViewController in the navController. This is pretty standard stuff, right? This is how I do it

我有UITabbarController和UINavigationController。我有一个UIView的子类我把它作为UIViewController的视图分配给navController。这是很标准的东西，对吧?我就是这么做的

_productCategoryView = [[ProductCategoryView alloc] initWithFrame:self.view.frame];
self.view = _productCategoryView;

This view has a UITableView as subView

这个视图有一个UITableView作为子视图

_productCategoryTableView = [[UITableView alloc] initWithFrame:self.frame style:UITableViewStylePlain];
_productCategoryTableView.separatorStyle = UITableViewCellSeparatorStyleNone;
_productCategoryTableView.backgroundColor = [UIColor clearColor];
[self addSubview:_productCategoryTableView];

For the sake of debugging I am setting self.backgroundColor = [UIColor blueColor] on the view.

为了调试，我设置了self。背景色= [UIColor blueColor]在视图上。

From the above initialization of tableView one might think that the view's and table's frame is same. However when I run in iOS 7, the view's origin is set behind the UINavigationBar. This is understandable because I am setting self.navigationBar.translucent = YES; in my subclass of UINavigationController. But what I don't understand is how come the table is sitting just below the navBar? Shouldn't it also start from (0, 0) which is behind the navBar? See screenshot Scenario 1 below. Notice the blue hue behind navBar

从上面对tableView的初始化可以看出，视图和表的框架是相同的。然而，当我在ios7中运行时，视图的起源被设置在UINavigationBar后面。这是可以理解的，因为我设置了self。navigationbar。半透明的=是的;在UINavigationController的子类中。但是我不明白的是为什么桌子就在导航条下面?它是不是也应该从(0,0)navBar后面开始?参见下面的截图场景1。注意导航条后面的蓝色色调

Now, I push another viewController on the navigation stack, simply by using [self.navigationController pushViewController.....]. Again I have a custom UIView with a tableView in it. However I also have a UILabel above this table, and again for debugging, I gave it a redColor. This time I am setting the label's origin to be almost same as the view's

现在，我在导航堆栈上推另一个viewController，通过使用[self。导航控制器pushViewController .....]。我有一个自定义的UIView，里面有tableView。但是，我在这个表上面也有一个UILabel，为了调试，我给了它一个红色。这一次，我将标签的起点设置为几乎与视图的起点相同

CGRect boundsInset = UIEdgeInsetsInsetRect(self.bounds, UIEdgeInsetsMake(10, 10, 10, 10));

CGSize textSize = [_titleLabel.text sizeWithFont:_titleLabel.font
                               constrainedToSize:CGSizeMake(boundsInset.size.width, MAXFLOAT)
                                   lineBreakMode:NSLineBreakByWordWrapping];
printSize(textSize);
_titleLabel.frame = CGRectMake(boundsInset.origin.x,
                               boundsInset.origin.y,
                               boundsInset.size.width,
                               textSize.height);

So, going by the logic above, the label should be visible, right? But this time it's not. This time the label is behind the navBar.

根据上面的逻辑，标签应该是可见的，对吧?但这次不是。这次标签在导航条后面。

Notice, the red hue behind navBar.

注意，导航条后面的红色色调。

I would really like to align the subView below the navBar consistently. My questions are

我真的希望将子视图始终对齐到导航条下面。我的问题是

1. How is the tableView offset by 64pixels (height of nav + status bar in iOS 7) automatically, even though it's frame is same as the view's?

1。虽然tableView的框架和视图的框架是一样的，但是它是如何自动被64px (iOS 7中nav +状态栏的高度)偏移的呢?

2. Why does that not happen in the second view?

2。为什么这不会发生在第二视图中?

3 个解决方案

#1

By default, UITableViewController's views are automatically inset in iOS7 so that they don't start below the navigation bar/status bar. This is controller by the "Adjust scroll view insets" setting on the Attributes Inspector tab of the UITableViewController in Interface Builder, or by the setAutomaticallyAdjustsScrollViewInsets: method of UIViewController.

默认情况下，UITableViewController的视图会自动插入iOS7中，这样它们就不会从导航栏/状态栏开始。这是控制器通过在接口构建器中的UITableViewController的属性检查器选项卡上的“调整滚动视图内嵌”设置，或者通过UIViewController的setautomaticallycontrollsscrollviewinsets:方法。

For a UIViewController's contents, if you don't want its view's contents to extend under the top/bottom bars, you can use the Extend Edges Under Top Bars/Under Bottom Bars settings in Interface Builder. This is accessible via the edgesForExtendedLayout property.

对于一个UIViewController的内容，如果您不希望它的视图内容扩展到顶部/底部栏下，您可以使用接口构建器中顶部栏/底部栏设置下的扩展边。可以通过edgesForExtendedLayout属性访问它。

#2

- (void)viewDidLoad {
    [super viewDidLoad];
    self.edgesForExtendedLayout = UIRectEdgeNone;
 }

Swift 2:

斯威夫特2:

self.edgesForExtendedLayout = UIRectEdge.None

Swift 3:

斯威夫特3:

self.edgesForExtendedLayout = []

#3

@Gank's answer is correct, but the best place to do this is on the UINavigationControllerDelegate (if you have one):

@Gank的答案是正确的，但最好的做法是在UINavigationControllerDelegate上(如果你有的话):

func navigationController(navigationController: UINavigationController, willShowViewController viewController: UIViewController, animated: Bool) {
    viewController.edgesForExtendedLayout = UIRectEdge.None
}