中心UIView没有重叠不同大小的邻居视图？

Question

我希望实现的目标，其中三个是UILabels：

规格：

1. left和right是UIViews。
2. middle居中，即使侧面视图的大小不同。
3. 在middle和left或middle和right之间发生碰撞时，middle中的文字会在left和{{{{}}}时被截断1}}不要改变。

问题：

我不能同时满足要求（2）和（3）。

• （2）通过right实现
  • 问题：没有截断，只是重叠middle.autoAlignAxisToSuperviewAxis(.Vertical)和leftLabel。
• （3）是通过rightLabel和middle.autoPinEdge(.Left, toEdge: .Right, ofView: leftLabel)的相同策略实现的。
  • 问题：rightLabel位于middle和leftLabel之间的区域，如果最后两个不具有相同的大小，则rightLabel不再是以超级视图为中心。

两个应用都会产生约束冲突，我不知道如何修复它，因此我的问题是：

如何将UILabel居中并将其截断为具有不同尺寸侧视图的重叠？

Answer 1

您只需要添加两个约束，一个是中间和左侧之间的水平间距，将关系设置为大于或等于＆＃39;和常量，例如10;另一种是中间和右边之间的水平间距，与约束一样的配置相同。

当中间标签的文本太长时，下面的约束将阻止中间与标签左右重叠。

添加示例代码：
我想你已经在故事板或代码中将约束设置为UILabel左右。以下示例用于配置UILabel中间

func setupConstraint() {
    self.middle = UILabel()
    self.middle!.backgroundColor = UIColor.yellowColor()
    self.view.addSubview(self.middle!)
    self.middle!.numberOfLines = 0
    self.middle!.translatesAutoresizingMaskIntoConstraints = false
    let middle = self.middle!
    var constraint = NSLayoutConstraint(item: middle, attribute: NSLayoutAttribute.Top, relatedBy: NSLayoutRelation.Equal, toItem: left, attribute: NSLayoutAttribute.Top, multiplier: 1, constant: 0)

    self.view.addConstraint(constraint)

    constraint = NSLayoutConstraint(item: middle, attribute: NSLayoutAttribute.Left, relatedBy: NSLayoutRelation.GreaterThanOrEqual, toItem: left, attribute: NSLayoutAttribute.Right, multiplier: 1, constant: 10)

    self.view.addConstraint(constraint)

    constraint = NSLayoutConstraint(item: right, attribute: NSLayoutAttribute.Left, relatedBy: NSLayoutRelation.GreaterThanOrEqual, toItem: middle, attribute: NSLayoutAttribute.Right, multiplier: 1, constant: 10)
    constraint.priority = 1000

    self.view.addConstraint(constraint)

    constraint = NSLayoutConstraint(item: middle, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 0)

    self.view.addConstraint(constraint)

    constraint = NSLayoutConstraint(item: middle, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.GreaterThanOrEqual, toItem: middle, attribute: NSLayoutAttribute.Height, multiplier: 1, constant: 100)

    self.view.addConstraint(constraint)

    self.middle!.text = "self.middle.translatesAutoresizingMaskIntoConstraints = false"
}

的 Sanpshot

Answer 2

我试图在操场上设置解决方案：

import UIKit
import XCPlayground

let viewController = UIViewController()
XCPlaygroundPage.currentPage.liveView = viewController.view

viewController.view.backgroundColor = UIColor.whiteColor()

let leftView = UIView()
leftView.translatesAutoresizingMaskIntoConstraints = false
leftView.backgroundColor = UIColor.greenColor()
let leftLabel = UILabel()
leftLabel.translatesAutoresizingMaskIntoConstraints = false
leftLabel.text = "leftleftleftleftleftleftleftleftleftleftleftleftleftleft"
leftView.addSubview(leftLabel)
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("|-2-[leftLabel]-2-|", options: [], metrics: nil, views: ["leftLabel": leftLabel]))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-2-[leftLabel]-2-|", options: [], metrics: nil, views: ["leftLabel": leftLabel]))

let middleView = UIView()
middleView.translatesAutoresizingMaskIntoConstraints = false
middleView.backgroundColor = UIColor.redColor()
let middleLabel = UILabel()
middleLabel.translatesAutoresizingMaskIntoConstraints = false
middleLabel.setContentCompressionResistancePriority(UILayoutPriorityDefaultLow, forAxis: .Horizontal)
middleLabel.text = "middle"
middleView.addSubview(middleLabel)
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("|-2-[middleLabel]-2-|", options: [], metrics: nil, views: ["middleLabel": middleLabel]))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-2-[middleLabel]-2-|", options: [], metrics: nil, views: ["middleLabel": middleLabel]))

let rightView = UIView()
rightView.translatesAutoresizingMaskIntoConstraints = false
rightView.backgroundColor = UIColor.greenColor()
let rightLabel = UILabel()
rightLabel.translatesAutoresizingMaskIntoConstraints = false
rightLabel.text = "right"
rightView.addSubview(rightLabel)
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("|-2-[rightLabel]-2-|", options: [], metrics: nil, views: ["rightLabel": rightLabel]))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-2-[rightLabel]-2-|", options: [], metrics: nil, views: ["rightLabel": rightLabel]))

viewController.view.addSubview(leftView)
viewController.view.addSubview(middleView)
viewController.view.addSubview(rightView)

NSLayoutConstraint(item: middleView, attribute: .CenterX, relatedBy: .Equal, toItem: viewController.view, attribute: .CenterX, multiplier: 1, constant: 0).active = true
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("|[leftView]->=8-[middleView]->=8-[rightView]|", options: [.AlignAllTop, .AlignAllBottom], metrics: nil, views: ["leftView": leftView, "middleView": middleView, "rightView": rightView]))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[leftView]", options: [], metrics: nil, views: ["leftView": leftView]))

结果如下：

更新（不在自己的视图中嵌入标签）：

import UIKit
import XCPlayground

let viewController = UIViewController()
XCPlaygroundPage.currentPage.liveView = viewController.view

viewController.view.backgroundColor = UIColor.whiteColor()

let leftLabel = UILabel()
leftLabel.translatesAutoresizingMaskIntoConstraints = false
leftLabel.backgroundColor = UIColor.greenColor()
leftLabel.text = "leftleftleftleftleftleftleftleftleftleftleftleftleftleft"

let middleLabel = UILabel()
middleLabel.translatesAutoresizingMaskIntoConstraints = false
middleLabel.setContentCompressionResistancePriority(UILayoutPriorityDefaultLow, forAxis: .Horizontal)
middleLabel.backgroundColor = UIColor.redColor()
middleLabel.text = "middle"

let rightLabel = UILabel()
rightLabel.translatesAutoresizingMaskIntoConstraints = false
rightLabel.backgroundColor = UIColor.greenColor()
rightLabel.text = "right"

viewController.view.addSubview(leftLabel)
viewController.view.addSubview(middleLabel)
viewController.view.addSubview(rightLabel)

NSLayoutConstraint(item: middleLabel, attribute: .CenterX, relatedBy: .Equal, toItem: viewController.view, attribute: .CenterX, multiplier: 1, constant: 0).active = true
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("|[leftLabel]->=8-[middleLabel]->=8-[rightLabel]|", options: [.AlignAllTop, .AlignAllBottom], metrics: nil, views: ["leftLabel": leftLabel, "middleLabel": middleLabel, "rightLabel": rightLabel]))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[leftLabel]", options: [], metrics: nil, views: ["leftLabel": leftLabel]))

希望它有所帮助：）