以编程方式相对于同级 UIView 的 iOS 自动布局

Question

我正在尝试在容器视图 (C1) 中添加 3 个自定义视图（redView、greenView、yellowView），这样所有自定义视图（redView、greenView、yellowView）都在以编程方式使用自动布局约束彼此下方。我希望容器视图（C1）的大小与其子视图的大小相同，所以输出应该是这样的。

红色、绿色和黄色视图只是为了显示预期的结果。其实我的自定义视图是这样的。

我正在使用自动布局来执行此操作。这是我执行此操作的代码。 RatingsSingleView 是我的自定义视图，如上图所示。

    @interface ViewController ()

    @property (weak, nonatomic) IBOutlet UIView *ratingsContainerView;

    @end

    @implementation ViewController



        - (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    UIView *previousTopView = self.ratingsContainerView;
    for(int i = 0; i < 3; ++i) {
        RatingsSingleView *view = [[RatingsSingleView alloc] init];
        view.translatesAutoresizingMaskIntoConstraints = NO;
        [self.ratingsContainerView addSubview:view];
        NSLayoutConstraint *topConstraint = nil;
        if(i == 0) {
            // Making the first subview top aligned to the container View top 
            topConstraint = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:previousTopView attribute:NSLayoutAttributeTop multiplier:1.0 constant:10.0];
        } else{
                    // Making the second and third subview top aligned to the view above it
            topConstraint = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:previousTopView attribute:NSLayoutAttributeBottom multiplier:1.0 constant:10.0];
        }

        NSLayoutConstraint *leftConstraint = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual toItem:self.ratingsContainerView attribute:NSLayoutAttributeLeft multiplier:1.0 constant:10.0];

        NSLayoutConstraint *rightConstraint = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeRight relatedBy:NSLayoutRelationEqual toItem:self.ratingsContainerView attribute:NSLayoutAttributeRight multiplier:1.0 constant:10.0];


        [self.ratingsContainerView addConstraint:topConstraint];
        [self.ratingsContainerView addConstraint:leftConstraint];
        [self.ratingsContainerView addConstraint:rightConstraint];


        if(i == 2) {
            // Adding last subview bottom to the container View bottom
            NSLayoutConstraint *bottomConstraint = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self.ratingsContainerView attribute:NSLayoutAttributeBottom multiplier:1.0 constant:-10.0];
             [self.ratingsContainerView addConstraint:bottomConstraint];

        }
        previousTopView = view;

    }
}
@end

所以问题是我没有得到预期的结果。我将容器视图固定在左右边缘，并在情节提要中将其高度设置为 0。一旦我运行上面的代码，我会得到以下结果。

有人可以指导我在这里做错了什么。谢谢

Answer 1

你给了一些错误的限制，我已经纠正了，试试这个...

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    UIView *previousTopView = self.ratingsContainerView;
    for(int i = 0; i < 3; ++i) {
        RatingsSingleView *view = [[RatingsSingleView alloc] init];
        view.translatesAutoresizingMaskIntoConstraints = NO;
        [self.ratingsContainerView addSubview:view];
        NSLayoutConstraint *topConstraint = nil;
        if(i == 0) {
            // Making the first subview top aligned to the container View top 
            topConstraint = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:previousTopView attribute:NSLayoutAttributeTop multiplier:1.0 constant:10.0];
        } else{
                // Making the second and third subview top aligned to the view above it
            topConstraint = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:previousTopView attribute:NSLayoutAttributeBottom multiplier:1.0 constant:10.0];
        }

        NSLayoutConstraint *leftConstraint = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.ratingsContainerView attribute:NSLayoutAttributeLeading multiplier:1.0 constant:10.0];

        NSLayoutConstraint *rightConstraint = [NSLayoutConstraint constraintWithItem:self.ratingsContainerView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:view attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:10.0];


        [self.ratingsContainerView addConstraint:topConstraint];
        [self.ratingsContainerView addConstraint:leftConstraint];
        [self.ratingsContainerView addConstraint:rightConstraint];

        if(i == 2) {
            // Adding last subview bottom to the container View bottom
            NSLayoutConstraint *bottomConstraint = [NSLayoutConstraint constraintWithItem:self.ratingsContainerView attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:view attribute:NSLayoutAttributeBottom multiplier:1.0 constant:10.0];
            [self.ratingsContainerView addConstraint:bottomConstraint];

        }
        previousTopView = view;

}