ios - 使用程序化自动布局时容器 View 的框架设置为 CGRectZero

Question

我有一个 UIView 子类，它将是一个工具提示，可以出现在任何 View Controller 的底部，以显示提示/错误消息/成功消息/等等。工具提示 View 有两个 subview :左侧的 UILabel 和右侧的 UIView，可以是任何东西(但通常用作 UIButton).

TooltipView.h

@interface TooltipView : UIView

@property (nonatomic, readonly) UILabel *textLabel;

@property (nonatomic) UIView *rightView;

TooltipView.m

static CGFloat const kSubviewToSuperviewSpacing = 7.0f;
static CGFloat const kTextLabelToRightViewHorizontalSpacing = 7.0f;

@implementation TooltipView

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];

    if (self) {
        _textLabel = [[UILabel alloc] init];
        _textLabel.numberOfLines = 0;
        [_textLabel setTranslatesAutoresizingMaskIntoConstraints:NO];

        [self addSubview:_textLabel];
    }

    return self;
}

- (void)setRightView:(UIView *)rightView {
    if (_rightView != rightView) {
        _rightView = rightView;

        [self addSubview:_rightView];

        [self setNeedsDisplay];
    }
}

- (BOOL)translatesAutoresizingMaskIntoConstraints {
    return NO;
}

- (void)updateConstraints {
    self.didUpdateConstraints = YES;

    [self addConstraint:[NSLayoutConstraint constraintWithItem:self.textLabel
                                                     attribute:NSLayoutAttributeLeading
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:self
                                                     attribute:NSLayoutAttributeLeading
                                                    multiplier:1.0f
                                                      constant:kSubviewToSuperviewSpacing]];

    NSMutableDictionary *metricsDictionary = [@{@"subviewToSuperviewSpacing": @(kSubviewToSuperviewSpacing)} mutableCopy];

    NSMutableDictionary *viewsDictionary = [@{@"textLabel": self.textLabel} mutableCopy];

    [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-subviewToSuperviewSpacing-[textLabel]-subviewToSuperviewSpacing-|"
                                                                 options:0
                                                                 metrics:metricsDictionary
                                                                   views:viewsDictionary]];

    if (self.rightView) {
        metricsDictionary[@"textLabelToRightViewHorizontalSpacing"] = @(kTextLabelToRightViewHorizontalSpacing);
        viewsDictionary[@"rightView"] = self.rightView;

        [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-subviewToSuperviewSpacing-[rightView]-subviewToSuperviewSpacing-|"
                                                                     options:0
                                                                     metrics:metricsDictionary
                                                                       views:viewsDictionary]];

        [self addConstraint:[NSLayoutConstraint constraintWithItem:self.rightView
                                                         attribute:NSLayoutAttributeTrailing
                                                         relatedBy:NSLayoutRelationEqual
                                                            toItem:self
                                                         attribute:NSLayoutAttributeTrailing
                                                        multiplier:1.0f
                                                          constant:kSubviewToSuperviewSpacing]];
    }

    [super updateConstraints];
}

我还有一个 View Controller 来使用 UILabel 作为 rightView 来测试它。它是 UIViewController 的子类，它唯一的方法是重写 loadView:

- (void)loadView {
    TooltipView *tooltipView = [[TooltipView alloc] initWithFrame:CGRectZero];

    tooltipView.textLabel.text = @"Test 1";

    UILabel *testLabel = [[UILabel alloc] initWithFrame:CGRectZero];
    testLabel.text = @"Hello there";
    [testLabel setTranslatesAutoresizingMaskIntoConstraints:NO];

    tooltipView.rightView = testLabel;

    self.view = tooltipView;

最后，在我想要显示工具提示的 View Controller 中，我将 TooltipViewController 添加为 subview Controller 。最终，这将由某些事件触发，但出于测试目的，我将其添加到 viewWillAppear: 中。

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    self.aViewController = [[TooltipViewController alloc] init];
    self.aViewController.view.backgroundColor = [UIColor whiteColor];

    [self addChildViewController:self.aViewController];

    [self.view addSubview:self.aViewController.view];

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[view]|"
                                                                  options:0
                                                                  metrics:nil
                                                                    views:@{@"view": self.aViewController.view}]];

    [self.aViewController.view addConstraint:[NSLayoutConstraint constraintWithItem:self.aViewController.view
                                                      attribute:NSLayoutAttributeHeight
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:nil
                                                      attribute:NSLayoutAttributeNotAnAttribute
                                                     multiplier:1.0f
                                                       constant:150.0f]];

    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.aViewController.view
                                                      attribute:NSLayoutAttributeBottom
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:self.view
                                                      attribute:NSLayoutAttributeBottom
                                                     multiplier:1.0f
                                                       constant:0.0f]];

    [self.aViewController didMoveToParentViewController:self];
}

但是，在运行时，textLabel 和 rightView 的框架似乎设置正确，但是 tooltipView 的框架设置了到 CGRectZero，这三个 View 都没有出现在屏幕上。

提前致谢!

编辑

我什至尝试过完全删除 textLabel 和 rightView，所以只是一个带有前导、尾随、底部和高度约束的普通 UIView。没有什么是模棱两可的，但 View 的框架仍然是 CGRectZero。

Answer 1

事实证明，解决方案只是在 TooltipView 的初始化程序中调用 setTranslatesAutoresizingMaskIntoConstraints 而不是覆盖该方法。这导致 View 正确显示。 h/t 亚伦汤普森 (https://twitter.com/aaptho/status/612815498661773312)。