如何以编程方式分配UIViews自动布局边缘以匹配超级视图？

Question

我有一个要添加到ViewController的模式视图，现在传统上我总是只根据屏幕大小调整大小，以便模式的背景可以覆盖整个屏幕，并具有一个较小的alpha值，以便可以看到内容。

使用我当前的应用程序，我允许用户更改方向，因此上述方法不起作用。 我试图找到一种以编程方式将与self.view相关的模式的所有自动布局边分配为0的方法。 我尝试了以下代码，但出现错误。

[self.view addSubview:self.viewPromptSignup];

self.viewPromptSignup.translatesAutoresizingMaskIntoConstraints = NO;

/* pin Left of child to left of parent */
[self.viewPromptSignup addConstraint:[NSLayoutConstraint constraintWithItem:self.view
                                                      attribute:NSLayoutAttributeLeft
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:self.viewPromptSignup
                                                      attribute:NSLayoutAttributeLeft
                                                     multiplier:1.0
                                                       constant:0]];

/* pin Right of child to right of parent */
[self.viewPromptSignup addConstraint:[NSLayoutConstraint constraintWithItem:self.view
                                                      attribute:NSLayoutAttributeRight
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:self.viewPromptSignup
                                                      attribute:NSLayoutAttributeRight
                                                     multiplier:1.0
                                                       constant:0]];

/* pin top of child to bottom of nav bar(or status bar if no nav bar) */
[self.viewPromptSignup addConstraint:[NSLayoutConstraint constraintWithItem:self.view
                                                      attribute:NSLayoutAttributeTop
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:self.viewPromptSignup
                                                      attribute:NSLayoutAttributeBottom
                                                     multiplier:1.0
                                                       constant:0]];

/* pin Top of nav bar to bottom of child view */
[self.viewPromptSignup addConstraint:[NSLayoutConstraint constraintWithItem:self.view
                                                      attribute:NSLayoutAttributeTop
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:self.viewPromptSignup
                                                      attribute:NSLayoutAttributeBottom
                                                     multiplier:1.0
                                                       constant:0]];

Answer 1

//Creating View
UIView *viewPromptSignup=[UIView new];
viewPromptSignup.translatesAutoresizingMaskIntoConstraints = NO;

[viewPromptSignup setBackgroundColor:[UIColor greenColor]];

//adding to Parent View
[self.view addSubview:viewPromptSignup];


//Top and Bottom Guide
id topGuide = self.topLayoutGuide;
id bottomGuide = self.bottomLayoutGuide;


NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings (viewPromptSignup, topGuide,bottomGuide);

[self.view addConstraints:
 [NSLayoutConstraint constraintsWithVisualFormat: @"V:[topGuide]-10-[viewPromptSignup]"
                                         options: 0
                                         metrics: nil
                                           views: viewsDictionary]
 ];
[self.view addConstraints:
 [NSLayoutConstraint constraintsWithVisualFormat: @"V:[viewPromptSignup]-10-[bottomGuide]"
                                         options: 0
                                         metrics: nil
                                           views: viewsDictionary]
 ];


// align viewPromptSignup from the left and right
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[viewPromptSignup]-0-|" options:0 metrics:nil views:viewsDictionary]];

Answer 2

您可以使用Masonry库，因为添加约束非常容易。

检查一下https://github.com/SnapKit/Masonry

使用此库，您可以像这样轻松设置约束：

[view1 mas_makeConstraints:^(MASConstraintMaker *make) {
    make.top.equalTo(superview.mas_top);
    make.left.equalTo(superview.mas_left);
    make.bottom.equalTo(superview.mas_bottom);
    make.right.equalTo(superview.mas_right);
}];

超级容易