如何避免使用程序化自动布局进行硬编码

Question

我在使用自动版式时遇到问题（我是新手），虽然我的约束按预期运行（一切都水平居中，垂直间距如我所愿），但当我转向横向时，底部按钮消失。

我知道发生这种情况是因为我已经根据纵向视图限制了我的对象，并且当我们移动到横向时高度和宽度值发生变化时这不再适用。我真的不知道如何在改变方向时考虑这些变化。有什么建议吗？

代码和截图如下：

-(void)setConstraints {
    [self.view removeConstraints:self.view.constraints];

    UIButton *cameraButton = self.cameraButton;
    UILabel *camera = self.videoLabel;
    UIButton *libraryButton = self.libraryButton;
    UILabel *library = self.libraryLabel;


    NSDictionary *views = NSDictionaryOfVariableBindings(camera, cameraButton, libraryButton, library);

    NSDictionary *metrics = @{@"horizontalSpacing":@500.0, @"verticalSpacing":@125};


    //set up top button to be horizontally centered
    NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"|-[cameraButton]-|"
                                                                   options:0
                                                                   metrics:nil
                                                                     views:views];

    //set up top button vertical from top of superview
    constraints = [constraints arrayByAddingObjectsFromArray:
                   [NSLayoutConstraint constraintsWithVisualFormat: @"V:|-175-[cameraButton]"
                                                           options:0
                                                           metrics:nil
                                                             views:views]];
    //set up top button label to be horizontally centered
    constraints = [constraints arrayByAddingObjectsFromArray:
                   [NSLayoutConstraint constraintsWithVisualFormat: @"|-[camera]-|"
                                                           options:0
                                                           metrics:nil
                                                             views:views]];

    //set up second button to be horizontally centered
    constraints = [constraints arrayByAddingObjectsFromArray:
                   [NSLayoutConstraint constraintsWithVisualFormat: @"|-[libraryButton]-|"
                                                           options:0
                                                           metrics:nil
                                                             views:views]];
    //set up label for second button to be horizontally centered
    constraints = [constraints arrayByAddingObjectsFromArray:
                   [NSLayoutConstraint constraintsWithVisualFormat: @"|-[library]-|"
                                                           options:0
                                                           metrics:nil
                                                             views:views]];

    //set up vertical constraints by spacing ALL objects appropriately
    constraints = [constraints arrayByAddingObjectsFromArray:
                   [NSLayoutConstraint constraintsWithVisualFormat: @"V:[cameraButton]-[camera]-verticalSpacing-[libraryButton]-[library]"
                                                           options:0
                                                           metrics:metrics
                                                             views:views]];


    self.libraryLabel.textAlignment = NSTextAlignmentCenter;
    self.videoLabel.textAlignment = NSTextAlignmentCenter;

    self.libraryLabel.backgroundColor = [UIColor redColor];

    [self.view addConstraints:constraints];

}

Answer 1

您得到的正是您所要求的。如果这不是您想要的，请不要要求！

想想你的垂直约束：

@"V:|-175-[cameraButton]"
@"V:[cameraButton]-[camera]-verticalSpacing-[libraryButton]-[library]"

从上到下构成了一个单一的约束链。当然，如果屏幕 比你的 175 短 加上你的 verticalSpacing 加上其他视图的尺寸和最小间距，底部视图将离开底部屏幕。

如果这不是您想要的，请更改您的设计，这样就不是您想要的了。例如，将您的一些视图从上到下放置，而将一些视图从下到上放置。或者允许你的一些空间改变为父视图高度的百分比。

如何避免使用程序化自动布局进行硬编码

how to avoid hardcoding with programmatic autolayout

user-interface

objective-c

interface-builder

ios

autolayout