Question

我需要一个没有xib的视图控制器。应该有一个完全填充到视图的webview。为此，我已将以下代码添加到loadView方法。

- (void)loadView {
    CGRect applicationFrame = [[UIScreen mainScreen] applicationFrame];
    UIView *view = [[UIView alloc] initWithFrame:applicationFrame];

    view.translatesAutoresizingMaskIntoConstraints = NO;
    [view setBackgroundColor:[UIColor greenColor]];
    [self setView:view];
//    //create webview
    self.webview = [[UIWebView alloc] initWithFrame:CGRectZero];
    self.webview.translatesAutoresizingMaskIntoConstraints = NO;
    [view addSubview:self.webview];
    [self.webview setBackgroundColor:[UIColor orangeColor]];
    [self.webview setDelegate:self];

    NSDictionary *viewBindings = NSDictionaryOfVariableBindings(view,_webview);
//    //add constraints
    [view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_webview]|" options:0 metrics:nil views:viewBindings]];
    [view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_webview]|" options:0 metrics:nil views:viewBindings]];

}

但这会将整个视图变为黑色。如果我执行[view addConstraints:...方法调用它显示绿色视图。我的代码出了什么问题？

Answer 1

我认为问题是父视图不应该将translatesAutoresizingMaskIntoConstraints设置为false。必须将该属性设置为false的唯一视图是您要应用autolayout的视图，在本例中为webView。如果您将view.translatesAutoresizingMaskIntoConstraints设置为false，则必须向view添加约束。

Answer 2

您不需要手动更改UIViewController的根视图，也许这就是为什么它不起作用。

我的建议是试试这个：

- (void) viewDidLoad {
    [super viewDidLoad];

    self.webview = [[UIWebView alloc] init];
    self.webview.translatesAutoresizingMaskIntoConstraints = NO;
    [view addSubview:self.webview];
    [self.webview setBackgroundColor:[UIColor orangeColor]];
    [self.webview setDelegate:self];

    NSDictionary *viewBindings = NSDictionaryOfVariableBindings(view,_webview);
    [view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[_webview]-0-|" options:0 metrics:nil views:viewBindings]];
    [view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[_webview]-0-|" options:0 metrics:nil views:viewBindings]];
    // put a breakpoint after this line to see the frame of your UIWebView. 
    // It should be the same as the view
    [self.view layoutIfNeeded];
}

这应该有用，UIWebView应全屏显示。祝你好运！

以编程方式添加autolayout约束将uiview变为黑色

2 个答案: