在 VFL 中创建垫片答案

【问题标题】：Creating Spacers in VFL在 VFL 中创建垫片
【发布时间】：2015-01-19 04:09:07
【问题描述】：

AutoLayoutbyExample via Apple Developer Documentation

任何人都有一个如何创建间隔视图以在 VFL 中将标签之间的间距设置为相等的示例？

labelsDictionary = [ "label1": label1,
                     "label2": label2,
                     "label3": label3,
                     "label4": label4 ]

let metrics = ["edgeSpacing": 20, "spacingBetween": 5, "labelWidth": 50]
let constraints = "H:|-(==edgeSpacing)-[label1(==labelWidth@999)]-[label2(==label1)]-[label3(==label1)]-[label3(==label1)]-[label4(==label1)]-(==edgeSpacing)-|"
self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat( format : constraints, 
                                                                   options : .allZeros, 
                                                                   metrics : metrics, 
                                                                     views : labelsDictionary))

我只是想知道如何在 Swift 中创建间隔，以确保标签之间的宽度始终相等但优先级最低。

【问题讨论】：

标签： ios objective-c swift autolayout visual-format-language

【解决方案1】：

您可以添加 3 个间隔视图，它们与 4 个标签混合。

label1-spacer1-label2-spacer2-label3-spacer3-label4

假设您在 containerView 中拥有所有 7 个视图。因为标签的宽度可能会根据其文本而变化，所以它们之间的间距最好是相等的。

self.containerView.removeConstraints(containerView.constraints())

let views = ["label1": label1,
    "label2": label2,
    "label3": label3,
    "label4": label4,
    "spacer1": spacer1,
    "spacer2": spacer2,
    "spacer3": spacer3
 ]
let metrics = ["edgeSpacing": 20, "spacingBetween": 5]

//make spacers have equal width, and greater than 5, make all views center align vertically
var constH = NSLayoutConstraint.constraintsWithVisualFormat("H:|-edgeSpacing-[label1]-[spacer1(>=spacingBetween)]-[label2]-[spacer2(==spacer1)]-[label3]-[spacer3(==spacer1)]-[label4]-edgeSpacing-|", options: .AlignAllCenterY, metrics: metrics, views: views)
view.addConstraints(constH)

//configure label1 vertical alignment
let constV = NSLayoutConstraint.constraintsWithVisualFormat("V:|-edgeSpacing-[label1]-edgeSpacing-|", options: .AlignAllCenterY, metrics: metrics, views: views)
view.addConstraints(constV)

//make spacers have equal height
let constVForSpacer1 = NSLayoutConstraint.constraintsWithVisualFormat("V:|-edgeSpacing-[spacer1(==spacer2)]-edgeSpacing-|", options: .allZeros, metrics: metrics, views: views)
view.addConstraints(constVForSpacer1)

let constVForSpacer2 = NSLayoutConstraint.constraintsWithVisualFormat("V:|-edgeSpacing-[spacer2(==spacer3)]-edgeSpacing-|", options: .allZeros, metrics: metrics, views: views)
view.addConstraints(constVForSpacer2)

【讨论】：

【解决方案2】：

没关系，我能够找到另一种方法来实现我想要的：

override func updateConstraints() {
  super.updateConstraints()
  for labelName in labelsDictionary.keys {
  self.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[\(labelName)]-|", options: .allZeros, metrics: nil, views: labelsDictionary))
}


self.addConstraint(NSLayoutConstraint(item: label1, attribute: .CenterX, relatedBy: .Equal, toItem: self, attribute: .Right, multiplier: 0.2, constant: 0))
self.addConstraint(NSLayoutConstraint(item: label2, attribute: .CenterX, relatedBy: .Equal, toItem: self, attribute: .Right, multiplier: 0.4, constant: 0))
self.addConstraint(NSLayoutConstraint(item: label3, attribute: .CenterX, relatedBy: .Equal, toItem: self, attribute: .Right, multiplier: 0.6, constant: 0))
self.addConstraint(NSLayoutConstraint(item: label4, attribute: .CenterX, relatedBy: .Equal, toItem: self, attribute: .Right, multiplier: 0.8, constant: 0))
}

【讨论】：