ios - UIView 固定到屏幕边缘，但框架保持 0,0

Question

我想将一个 UIView 插入到覆盖整个屏幕的 View 层次结构中。我的方法是创建一个 UIView 实例，将其添加到主视图，然后添加约束以将我的新 View 的边缘固定到父 View 。 UIViews 本身没有固有的内容大小，但是通过将边缘固定到 superview，UIView 应该有一个更大的框架。

[self.view setTranslatesAutoresizingMaskIntoConstraints:NO];
UIView *inviteCodeView =  [[UIView alloc] initWithFrame:CGRectZero];
inviteCodeView.opaque = NO;
inviteCodeView.alpha = 0.5;
inviteCodeView.backgroundColor = [UIColor colorWithWhite:0.3 alpha:1];
[inviteCodeView setTranslatesAutoresizingMaskIntoConstraints:NO];

inviteCodeView.backgroundColor = [UIColor redColor];
[self.view addSubview:inviteCodeView];
NSDictionary *views = NSDictionaryOfVariableBindings(inviteCodeView);

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[inviteCodeView]-0-|" options:0 metrics:nil views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[inviteCodeView]-0-|" options:0 metrics:nil views:views]];

可能出了什么问题，或者我对 Autolayout 的理解不正确？

Answer 1

虽然这不能直接回答您关于自动布局的问题，但我发现没有它，大大您想做的事会更容易。只需将 View 的框架设置为 View Controller 的框架，并将 View 的自动调整大小掩码设置为灵活的高度和宽度，框架将自动调整大小没问题。

UIView *inviteCodeView =  [[UIView alloc] initWithFrame:self.view.frame];
inviteCodeView.opaque = NO;
inviteCodeView.alpha = 0.5;
inviteCodeView.backgroundColor = [UIColor colorWithWhite:0.3 alpha:1];
inviteCodeView.autoresizingMask = UIViewAutoresizingFlexibleHeight + UIViewAutoresizingFlexibleWidth;
[self.view addSubview:inviteCodeView];

此外，使用您最初提供的代码，如果您删除第一行，您将 super View 的 setTranslatesAutoresizingMaskIntoConstraints 设置为 NO，则一切正常:

//    [self.view setTranslatesAutoresizingMaskIntoConstraints:NO];
    UIView *inviteCodeView =  [[UIView alloc] initWithFrame:CGRectZero];
    inviteCodeView.opaque = NO;
    inviteCodeView.alpha = 0.5;
    inviteCodeView.backgroundColor = [UIColor colorWithWhite:0.3 alpha:1];
    [inviteCodeView setTranslatesAutoresizingMaskIntoConstraints:NO];

    inviteCodeView.backgroundColor = [UIColor redColor];
    [self.view addSubview:inviteCodeView];
    NSDictionary *views = NSDictionaryOfVariableBindings(inviteCodeView);

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[inviteCodeView]-0-|" options:0 metrics:nil views:views]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[inviteCodeView]-0-|" options:0 metrics:nil views:views]];