UISegmentedControl随着自动版式标题产生位置偏移 [英] UISegmentedControl With AutoLayout Misaligns Title

问题描述

我有一个自定义的UITableViewCell是对左侧的 UISegmentedControl 右边的标签。我刚开始习惯在code。使用自动布局，而这正是我在我的自定义单元格（使用的的UIView +自动版式）：

I have a custom UITableViewCell that has a label on the left side a UISegmentedControl on the right. I'm just getting used to using Auto Layout in code, and this is what I have in my custom cell (using UIView+AutoLayout):

-(void)updateConstraints
{
    self.titleLabel.translatesAutoresizingMaskIntoConstraints = NO;
    self.segmentedControl.translatesAutoresizingMaskIntoConstraints = NO;

    [self.titleLabel pinToSuperviewEdges:JRTViewPinLeftEdge inset:DB_AUTOLAYOUT_DEFAULT_INSET];
    [self.titleLabel centerInContainerOnAxis:NSLayoutAttributeCenterY];
    [self.segmentedControl pinToSuperviewEdges:JRTViewPinRightEdge inset:DB_AUTOLAYOUT_DEFAULT_INSET];
    [self.segmentedControl pinAttribute:NSLayoutAttributeBaseline
                            toAttribute:NSLayoutAttributeBaseline
                                 ofItem:self.titleLabel];

    [super updateConstraints];
}

我的问题是，分段控制的第一个冠军总是错位：

My problem is that the segmented control's first title is always misaligned:

这是它看起来像在iOS 6：

This is what it looks like on iOS 6:

和iOS上的7：

And on iOS 7:

所以，第一个问题是：我该如何解决这个问题？

So first question is: How do I fix this?

其他，切的问题：我是通过把汽车布局code在 updateConstraints 做正确的事情，或者我应该只是申请的限制，一旦

Other, tangential question: Am I doing the right thing by putting auto layout code in updateConstraints or should I just apply the constraints once?

推荐答案

在短距离UIView.h

In short from UIView.h

如果你做你的约束在-updateConstraints成立，你可能从来没有收到updateConstraints如果没有人做的约束。要解决这个鸡和蛋的问题，重写这个方法返回YES。

If you do all of your constraint set up in -updateConstraints, you might never even receive updateConstraints if no one makes a constraint. To fix this chicken and egg problem, override this method to return YES.

+ (BOOL)requiresConstraintBasedLayout {
        return YES; 
}

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