UIView 在 iOS7 但没有在 iOS8

Question

我创建了一个自定义视图以在圆圈内显示 2 个标签。它应该看起来像这样：

但在 iOS 7 中它看起来像这样：

发生这种情况是因为应该将标签贴在 top/bottom 上的约束帽由于某种原因被破坏了，但仅限于 iOS 7。我收到以下错误：

(
    "<NSLayoutConstraint:0x7f96e500a540 H:|-(-1)-[UILabel:0x7f96e2dd84d0]   (Names: '|':UIView:0x7f96e2df6350 )>" )

Will attempt to recover by breaking constraint  <NSLayoutConstraint:0x7f96e500a540 H:|-(-1)-[UILabel:0x7f96e2dd84d0]   (Names: '|':UIView:0x7f96e2df6350 )>

我已经确认这些实际上是调用的约束（我只举了一个错误作为例子）

self.dayLabelStickButtomConstraint
self.monthLabelStickTopConstraint

这是自定义视图的代码，谁能理解为什么它在 iOS 7 而不是 8？

- (instancetype) initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder:aDecoder];
    if (self) {
        [self initiateValues];
        [self buildHeirarchy];
    }
    return self;
}

- (instancetype) initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self initiateValues];
        [self buildHeirarchy];
    }
    return self;
}

-(void)initiateValues{
    self.fillColor = [UIColor blackColor];


    self.month = @"jan";
    self.monthFontSize = 8.0f;
    self.monthTextColor = [UIColor blackColor];
    self.monthLabelInsetDistance = 1.0f;

    self.day = @"01";
    self.dayFontSize = 12.0f;
    self.dayTextColor = [UIColor blackColor];
    self.dayLabelInsetDistance = 1.0f;
}

-(void)buildHeirarchy{
    self.innerContainer = [[UIView alloc] initWithFrame:CGRectInset(self.bounds, 5.0, 5.0)];
    [self.innerContainer setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self addSubview:self.innerContainer];
    [self addConstraint:[NSLayoutConstraint constraintWithItem:self.innerContainer
                                                     attribute:NSLayoutAttributeCenterX
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:self
                                                     attribute:NSLayoutAttributeCenterX
                                                    multiplier:1.0
                                                      constant:0.0]];
    [self addConstraint:[NSLayoutConstraint constraintWithItem:self.innerContainer
                                                     attribute:NSLayoutAttributeCenterY
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:self
                                                     attribute:NSLayoutAttributeCenterY
                                                    multiplier:1.0
                                                      constant:0.0]];
    [self addConstraint:[NSLayoutConstraint constraintWithItem:self.innerContainer
                                                     attribute:NSLayoutAttributeWidth
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:self
                                                     attribute:NSLayoutAttributeWidth
                                                    multiplier:0.7
                                                      constant:0.0]];
    [self addConstraint:[NSLayoutConstraint constraintWithItem:self.innerContainer
                                                     attribute:NSLayoutAttributeHeight
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:self
                                                     attribute:NSLayoutAttributeHeight
                                                    multiplier:0.7
                                                      constant:0.0]];


    self.monthLabel = [[UILabel alloc] initWithFrame:CGRectInset(self.bounds, 5.0, 5.0)];
    [self.monthLabel setTranslatesAutoresizingMaskIntoConstraints:NO];
    self.monthLabel.textAlignment = NSTextAlignmentCenter;
    [self.innerContainer addSubview:self.monthLabel];

    [self.innerContainer addConstraint:[NSLayoutConstraint constraintWithItem:self.monthLabel
                                                                    attribute:NSLayoutAttributeCenterX
                                                                    relatedBy:NSLayoutRelationEqual
                                                                       toItem:self.innerContainer
                                                                    attribute:NSLayoutAttributeCenterX
                                                                   multiplier:1.0
                                                                     constant:0.0]];

    NSLayoutConstraint *monthTopConstraint = [NSLayoutConstraint constraintWithItem:self.monthLabel
                                                                          attribute:NSLayoutAttributeTopMargin
                                                                          relatedBy:NSLayoutRelationEqual
                                                                             toItem:self.innerContainer
                                                                          attribute:NSLayoutAttributeTopMargin
                                                                         multiplier:1.0
                                                                           constant:self.monthLabelInsetDistance];
    self.monthLabelStickTopConstraint = monthTopConstraint;
    [self.innerContainer addConstraint:self.monthLabelStickTopConstraint];


    self.dayLabel = [[UILabel alloc] initWithFrame:CGRectInset(self.bounds, 5.0, 5.0)];
    [self.dayLabel setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.innerContainer addSubview:self.dayLabel];
    self.dayLabel.textAlignment = NSTextAlignmentCenter;

    [self.innerContainer addConstraint:[NSLayoutConstraint constraintWithItem:self.dayLabel
                                                                    attribute:NSLayoutAttributeCenterX
                                                                    relatedBy:NSLayoutRelationEqual
                                                                       toItem:self.innerContainer
                                                                    attribute:NSLayoutAttributeCenterX
                                                                   multiplier:1.0
                                                                     constant:0.0]];

    NSLayoutConstraint *dayButtomConstraint = [NSLayoutConstraint constraintWithItem:self.dayLabel
                                                                           attribute:NSLayoutAttributeBottomMargin
                                                                           relatedBy:NSLayoutRelationEqual
                                                                              toItem:self.innerContainer
                                                                           attribute:NSLayoutAttributeBottomMargin
                                                                          multiplier:1.0
                                                                            constant:self.dayLabelInsetDistance];

    self.dayLabelStickButtomConstraint = dayButtomConstraint;
    [self.innerContainer addConstraint:self.dayLabelStickButtomConstraint];



}

-(void)layoutSubviews{
    // get the graphics context
    if (!self.backgroundColorRoundView) {

        self.backgroundColorRoundView = [[UIView alloc]initWithFrame:self.bounds];
        [self addSubview:self.backgroundColorRoundView];
        [self sendSubviewToBack:self.backgroundColorRoundView];
        self.backgroundColorRoundLayer = [CAShapeLayer new];
        UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:self.backgroundColorRoundView.bounds];
        self.backgroundColorRoundLayer.path = path.CGPath;
        //imageMaskLayer.fillColor = self.fillColor.CGColor;
        [self.backgroundColorRoundView.layer addSublayer:self.backgroundColorRoundLayer];
    }
    self.backgroundColorRoundView.frame = self.bounds;
    self.backgroundColorRoundLayer.frame = self.bounds;
    [self updateViews];
    [super layoutSubviews];

}

-(void)updateViews{
    self.monthLabel.textColor = self.monthTextColor;
    self.dayLabel.textColor = self.dayTextColor;
    self.backgroundColorRoundLayer.fillColor = self.fillColor.CGColor;
}

-(void)updateConstraints{
    self.dayLabelStickButtomConstraint.constant = self.dayLabelInsetDistance;
    self.monthLabelStickTopConstraint.constant = self.monthLabelInsetDistance;

    [super updateConstraints];

}

Answer 1

经过一番折腾后，答案就在于约束本身。一旦我从顶部边距、底部边距切换到顶部和底部，它就起作用了

UIView 在 iOS7 但没有在 iOS8

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