Ios 无法关闭UIWebView和UINavigationBar之间的间隙

在我的项目中，我将

UIWebView

放在

UINavigationBar

下，然后设置

UIWebView

以占据除

UINavigationBar

之外的屏幕的其余部分。但我发现两个控件之间存在一些差距。左边缘和

UIWebView

左侧之间也有间隙。知道我错过了什么吗

这是我的更新代码： 在

UIView+AutoLayout

中：（此类别将所有视图的

translatesAutoResizengMaskintoConstraints

属性设置为

NO

）

在ViewController中：

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.navigationBar = [UINavigationBar autolayoutView];
    UINavigationItem *backToListItem = [[UINavigationItem alloc] init];
    UIBarButtonItem *listItem = [[UIBarButtonItem alloc] initWithTitle:@"List"   style:UIBarButtonItemStylePlain target:self action:@selector(listButtonPressed:)];
    backToListItem.leftBarButtonItem = listItem;

    self.navigationBar.items = [NSArray arrayWithObject:backToListItem];

    [self.view addSubview:self.navigationBar];

    self.webView = [TNSWebView autolayoutView];

    [self.view addSubview:self.webView];

    NSDictionary *views = NSDictionaryOfVariableBindings(_navigationBar, _webView);
    [self.view addConstraints:[NSLayoutConstraint
                           constraintsWithVisualFormat:@"|[_navigationBar]|"
                           options:0 metrics:nil
                           views:views]];
    [self.view addConstraints:[NSLayoutConstraint
                                 constraintsWithVisualFormat:@"V:|[_navigationBar]->=0-[_webView]|"
                                 options:0 metrics:nil
                                 views:views]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_webView]|" options:0 metrics:nil views:views]];
    [self.webView setupVideoPlayer:self.videoId];
}

在

lldb

中使用

po[[UIWindow-keyWindow]recursiveDescription]

命令，我得到了这个结果

    | <UIView: 0x1d23f880; frame = (0 20; 768 1004); autoresize = RM+BM; layer = <CALayer: 0x1d23cba0>>
   |    | <UINavigationBar: 0x1d00a4b0; frame = (0 0; 768 44); gestureRecognizers = <NSArray: 0x1d015ff0>; layer = <CALayer: 0x1d0c8f60>>
   |    |    | <_UINavigationBarBackground: 0x1d010250; frame = (0 0; 768 44); opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d011140>>
   |    |    |    | <UIImageView: 0x1d0d26b0; frame = (0 44; 768 3); opaque = NO; autoresize = W+TM; userInteractionEnabled = NO; layer = <CALayer: 0x1d23fbd0>>
   |    |    | <UINavigationItemView: 0x1d016740; frame = (384 22; 0 0); opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d016840>>
   |    |    | <UINavigationButton: 0x1d013ff0; frame = (7 7; 48 30); opaque = NO; layer = <CALayer: 0x1d014170>>
   |    |    |    | <UIImageView: 0x1c5d9ca0; frame = (0 0; 48 30); clipsToBounds = YES; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1c58b330>>
   |    |    |    | <UIButtonLabel: 0x1d0144c0; frame = (13 7; 22 15); text = 'List'; clipsToBounds = YES; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d014560>>
   |    | <TNSWebView: 0x1d016bc0; baseClass = UIWebView; frame = (0 44; 768 960); layer = <CALayer: 0x1d016ca0>>
   |    |    | <_UIWebViewScrollView: 0x1d012390; frame = (0 0; 768 960); clipsToBounds = YES; autoresize = H; gestureRecognizers = <NSArray: 0x1d011380>; layer = <CALayer: 0x1d0125e0>; contentOffset: {0, 0}>
   |    |    |    | <UIImageView: 0x1d00f2a0; frame = (0 0; 10 10); transform = [-1, 0, -0, -1, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00f300>>
   |    |    |    | <UIImageView: 0x1d00f210; frame = (0 0; 10 10); transform = [0, 1, -1, 0, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00f270>>
   |    |    |    | <UIImageView: 0x1d00f180; frame = (0 0; 10 10); transform = [0, -1, 1, 0, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00f1e0>>
   |    |    |    | <UIImageView: 0x1d00efb0; frame = (0 0; 10 10); alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00f150>>
   |    |    |    | <UIImageView: 0x1d00ef20; frame = (-4.5 4.5; 10 1); transform = [0, 1, -1, 0, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00ef80>>
   |    |    |    | <UIImageView: 0x1d00ee90; frame = (-4.5 4.5; 10 1); transform = [0, -1, 1, 0, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00eef0>>
   |    |    |    | <UIImageView: 0x1d00ee00; frame = (0 0; 1 10); transform = [-1, 0, -0, -1, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00ee60>>
   |    |    |    | <UIImageView: 0x1d00ec30; frame = (0 0; 1 10); alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00edd0>>
   |    |    |    | <UIImageView: 0x1d00eba0; frame = (0 954; 768 6); alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00ec00>>
   |    |    |    | <UIImageView: 0x1d00fcd0; frame = (0 0; 768 6); transform = [-1, 0, -0, -1, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1d00fe70>>
   |    |    |    | <UIWebBrowserView: 0x1dbf2400; frame = (0 0; 768 960); gestureRecognizers = <NSArray: 0x1d014c40>; layer = <UIWebLayer: 0x1d017d00>>
   |    |    |    |    | <TileHostLayer: 0x1d017e70> (layer)
   |    |    |    |    |    | <TileLayer: 0x1c5511a0> (layer)
   |    |    |    |    |    | <TileLayer: 0x1c551210> (layer)
   |    |    |    |    |    | <TileLayer: 0x1c551250> (layer)
   |    |    |    |    |    | <TileLayer: 0x1c551290> (layer)

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更新的屏幕截图：

通过将导航栏的高度更改为44并使用recursiveDescription命令，我得到：

$0 = 0x2008f680 <UIWindow: 0x1ed814f0; frame = (0 0; 768 1024); autoresize = W+H; layer = <UIWindowLayer: 0x1ed815f0>>
   | <UIView: 0x20167680; frame = (0 20; 768 1004); autoresize = RM+BM; layer = <CALayer: 0x1ed0ea50>>
   |    | <UINavigationBar: 0x1ed14b70; frame = (0 0; 768 44); gestureRecognizers = <NSArray: 0x20081bd0>; layer = <CALayer: 0x1ed09ff0>>
   |    |    | <_UINavigationBarBackground: 0x1ed8b9b0; frame = (0 0; 768 44); opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x1ed08570>>
   |    |    |    | <UIImageView: 0x2007aa90; frame = (0 44; 768 3); opaque = NO; autoresize = W+TM; userInteractionEnabled = NO; layer = <CALayer: 0x200f9640>>
   |    |    | <UINavigationItemView: 0x20053320; frame = (384 22; 0 0); opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x200f9c30>>
   |    |    | <UINavigationButton: 0x200fa980; frame = (7 7; 48 30); opaque = NO; layer = <CALayer: 0x200f50c0>>
   |    |    |    | <UIImageView: 0x2016af20; frame = (0 0; 48 30); clipsToBounds = YES; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x2016af80>>
   |    |    |    | <UIButtonLabel: 0x2004e420; frame = (13 7; 22 15); text = 'List'; clipsToBounds = YES; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x200f8040>>
   |    | <TNSWebView: 0x2004d660; baseClass = UIWebView; frame = (0 44; 768 960); layer = <CALayer: 0x20053f20>>
   |    |    | <_UIWebViewScrollView: 0x2004a230; frame = (0 0; 768 960); clipsToBounds = YES; autoresize = H; gestureRecognizers = <NSArray: 0x20049700>; layer = <CALayer: 0x2004a6c0>; contentOffset: {0, 0}>
   |    |    |    | <UIImageView: 0x20048d50; frame = (0 0; 10 10); transform = [-1, 0, -0, -1, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x20048db0>>
   |    |    |    | <UIImageView: 0x20048cc0; frame = (0 0; 10 10); transform = [0, 1, -1, 0, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x20048d20>>
   |    |    |    | <UIImageView: 0x20048c30; frame = (0 0; 10 10); transform = [0, -1, 1, 0, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x20048c90>>
   |    |    |    | <UIImageView: 0x200f7c50; frame = (0 0; 10 10); alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x20048c00>>
   |    |    |    | <UIImageView: 0x200f7bc0; frame = (-4.5 4.5; 10 1); transform = [0, 1, -1, 0, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x200f7c20>>
   |    |    |    | <UIImageView: 0x200f7b30; frame = (-4.5 4.5; 10 1); transform = [0, -1, 1, 0, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x200f7b90>>
   |    |    |    | <UIImageView: 0x200f7a30; frame = (0 0; 1 10); transform = [-1, 0, -0, -1, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x200f7b00>>
   |    |    |    | <UIImageView: 0x200f7890; frame = (0 0; 1 10); alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x200f7a00>>
   |    |    |    | <UIImageView: 0x200fad20; frame = (0 954; 768 6); alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x200fad80>>
   |    |    |    | <UIImageView: 0x200fab80; frame = (0 0; 768 6); transform = [-1, 0, -0, -1, 0, 0]; alpha = 0; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x200facf0>>
   |    |    |    | <UIWebBrowserView: 0x1fb37600; frame = (0 0; 768 960); gestureRecognizers = <NSArray: 0x20049910>; layer = <UIWebLayer: 0x200f81c0>>
   |    |    |    |    | <TileHostLayer: 0x2004ed10> (layer)
   |    |    |    |    |    | <TileLayer: 0x20168820> (layer)
   |    |    |    |    |    | <TileLayer: 0x20168890> (layer)
   |    |    |    |    |    | <TileLayer: 0x201688d0> (layer)
   |    |    |    |    |    | <TileLayer: 0x20168910> (layer)

$0=0x2008f680
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也许您需要查看Web视图的查看模式。 在故事板或xib上，查看左侧面板，选择属性检查器，检查webView的视图模式选择（例如缩放填充，AspectFit，AspectFill..）。

更新 我把一切都收回。您的问题不在于视图布局。我认为您的问题在于，您正在加载到web视图中的web内容周围有边框（或填充或边距）。你会发现这很有用。它解释了如何使用Safari中的Web Inspector（在Mac上）调试在模拟器或设备上运行的

UIWebView

中的内容。我认为，如果您检查web内容中的视频元素，您会发现它与视口的上边缘和左边缘不齐平

起初的 我猜当您在

viewDidLoad

中查看导航栏时，它的高度设置不正确。现在检查刚刚创建的视图框架还为时过早

iOS应用程序在“运行循环”中花费时间，如下所示：

while (1) {
    Event phase: process one event (e.g. touch event, timer firing, local or push notification, etc.)
    Layout phase: update the frames of new views and views with added or removed subviews
    Draw phase: draw the contents of views that need to be drawn
    Wait for the next event to arrive
}

将视图添加到视图层次结构时，将计划在布局阶段对其进行布局。直到布局阶段完成，您才可以依靠新视图来获得正确的框架

通过编写

UIView

的子类（或根据需要编写任何其他视图类的子类）并重写其

layoutSubviews

方法，可以进入布局阶段。或者可以在视图控制器中实现

viewdilayoutsubviews

方法。我建议使用

UIView

子类并覆盖

layoutSubviews

，但您可能会发现只实现

viewdilayoutsubviews

更方便：

- (void)viewDidLayoutSubviews {
    [super viewDidLayoutSubviews];
    [self layoutWebView];
}

- (void)layoutWebView {
    CGRect frame = self.view.bounds;
    CGFloat navBarHeight = self.navigationBar.frame.size.height;
    frame.origin.y = navBarHeight;
    frame.size.height -= navBarHeight;
    self.webView.frame = frame;
}

或者，如果部署目标是iOS 6或更高版本，则可以使用“自动布局”将导航栏的下边缘固定到web视图的上边缘。将其放入

viewDidLoad

：

[self.view addLayoutConstraints:[NSLayoutConstraint
    constraintsWithVisualFormat:@"|V:[_navigationBar][_webView]|"
    options:0 metrics:nil
    views:NSDictionaryOfVariableBindings(_navigationBar, _webView)]];

---

现在，我认为在你的应用程序中特别发生的是，当你创建

UINavigationBar

时，你指定的高度是50，但是

UINavigationBar

想要的高度是44。因此，在布局阶段，导航栏将自身调整为44点高。由于在布局过程中您没有做任何事情来修复web视图的框架，因此web视图在顶级视图的上边缘下方仍保留50个点，留下6个点的间隙。因此，您可以在创建导航栏时将其高度更改为44。^）

我不使用故事板，我的xib文件是空的。我通过编程方式添加UIView。我已将UINavigationBar的高度更改为44。我还将代码更改为使用layoutConstraint。但这一次，UIWebView根本不显示。我可以听到视频在web视图中播放的声音，因此我认为这是一个布局问题。我不知道您为什么要在视觉格式中使用

->=0-

来分隔视图。这允许在视图之间进行任意程度的分隔，并且是不明确的，因此允许自动布局在视图之间留有间隙。我建议的视觉格式告诉auto layout视图的边缘之间不能有间隙。我尝试过不添加任何内容以及

->=0-

，但它们都不适合我。此外，您可能应该在导航栏和web视图上将

TranslatesAutoResizengMackinToConstraints

设置为

否

。如果您不这样做，我希望您的控制台中会出现自动布局警告。此外，您还需要在web视图上设置水平约束，就像在导航栏上一样。您的

递归描述

有些可疑之处。您的

TNSWebView

具有正确的框架，但是

UIWebView

即使不显示任何内容，也应该具有子体，以

UIWebView开头
[self.view addLayoutConstraints:[NSLayoutConstraint
    constraintsWithVisualFormat:@"|V:[_navigationBar][_webView]|"
    options:0 metrics:nil
    views:NSDictionaryOfVariableBindings(_navigationBar, _webView)]];