topLayoutGuide儿童视图控制器 [英] topLayoutGuide in child view controller

问题描述

我有一个 UIPageViewController 半透明的状态栏和导航栏。它的 topLayoutGuide 64像素，符合市场预期。

I have a UIPageViewController with translucent status bar and navigation bar. Its topLayoutGuide is 64 pixels, as expected.

不过，子视图控制器 UIPageViewController 报告的0像素的 topLayoutGuide ，即使它们是状态栏和导航栏下方显示。

However, the child view controllers of the UIPageViewController report a topLayoutGuide of 0 pixels, even if they're shown under the status bar and navigation bar.

这是预期的行为？如果是这样，什么是下一个定位子视图控制器的观点的最好办法真正的 topLayoutGuide ？

Is this the expected behavior? If so, what's the best way to position a view of a child view controller under the real topLayoutGuide?

（短期使用 parentViewController.topLayoutGuide ，我会考虑一个黑客）

(short of using parentViewController.topLayoutGuide, which I'd consider a hack)

推荐答案

的答案可能是正确的，我还是发现自己有旅游的围堵树高达找到合适的父视图控制器，让你形容为真正的 topLayoutGuide 。这样我可以手动执行 automaticallyAdjustsScrollViewInsets 。

While this answer might be correct, I still found myself having to travel the containment tree up to find the right parent view controller and get what you describe as the "real topLayoutGuide". This way I can manually implement automaticallyAdjustsScrollViewInsets.

这是我正在做的：

在我的表视图控制器（的UIViewController 的一个子类实际上），我有这样的：

In my table view controller (a subclass of UIViewController actually), I have this:

- (void)viewWillLayoutSubviews {
    [super viewWillLayoutSubviews];

    _tableView.frame = self.view.bounds;

    const UIEdgeInsets insets = (self.automaticallyAdjustsScrollViewInsets) ? UIEdgeInsetsMake(self.ms_navigationBarTopLayoutGuide.length,
                                                                                               0.0,
                                                                                               self.ms_navigationBarBottomLayoutGuide.length,
                                                                                               0.0) : UIEdgeInsetsZero;
    _tableView.contentInset = _tableView.scrollIndicatorInsets = insets;
}

通知的UIViewController 类的方法，这就是我如何实现它们：

Notice the category methods in UIViewController, this is how I implemented them:

@implementation UIViewController (MSLayoutSupport)

- (id<UILayoutSupport>)ms_navigationBarTopLayoutGuide {
    if (self.parentViewController &&
        ![self.parentViewController isKindOfClass:UINavigationController.class]) {
        return self.parentViewController.ms_navigationBarTopLayoutGuide;
    } else {
        return self.topLayoutGuide;
    }
}

- (id<UILayoutSupport>)ms_navigationBarBottomLayoutGuide {
    if (self.parentViewController &&
        ![self.parentViewController isKindOfClass:UINavigationController.class]) {
        return self.parentViewController.ms_navigationBarBottomLayoutGuide;
    } else {
        return self.bottomLayoutGuide;
    }
}

@end

希望这有助于：）

Hope this helps :)

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