编程方式创建约束 - 2盒

Question

我想创建以下结果：

由于只有手动创建NSLayoutConstraints。但目前我只有一个蓝色框，或者（如果我不添加UIButton）正确的红色视图。

let newView = UIView() 
    newView.backgroundColor = UIColor.redColor() 
    newView.translatesAutoresizingMaskIntoConstraints = false 
    view.addSubview(newView) 

    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Trailing, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Trailing, multiplier: 1, constant: 0) 
    view.addConstraint(verticalConstraint) 

    let topContraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Top, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Top, multiplier: 1, constant: 0) 
    view.addConstraint(topContraint) 

    let bottomContraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Bottom, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Bottom, multiplier: 1, constant: 0) 
    view.addConstraint(bottomContraint) 

    let widthConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 200) 
    view.addConstraint(widthConstraint) 



    let disableButton = UIButton() 
    disableButton.backgroundColor = UIColor.blueColor() 
    disableButton.translatesAutoresizingMaskIntoConstraints = false 
    view.addSubview(disableButton) 

    let leadingConstraint = NSLayoutConstraint(item: disableButton, attribute: NSLayoutAttribute.Leading, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Leading, multiplier: 1, constant: 0) 
    view.addConstraint(leadingConstraint) 

    let topBContraint = NSLayoutConstraint(item: disableButton, attribute: NSLayoutAttribute.Top, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Top, multiplier: 1, constant: 0) 
    view.addConstraint(topBContraint) 

    let bottomBContraint = NSLayoutConstraint(item: disableButton, attribute: NSLayoutAttribute.Bottom, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Bottom, multiplier: 1, constant: 0) 
    view.addConstraint(bottomBContraint) 

    let trailingConstraint = NSLayoutConstraint(item: disableButton, attribute: NSLayoutAttribute.Trailing, relatedBy: NSLayoutRelation.Equal, toItem: newView, attribute: NSLayoutAttribute.Trailing, multiplier: 1, constant: 0) 
    view.addConstraint(trailingConstraint) 

任何人都可以帮我解决什么是错的吗？有什么区别，我以哪种顺序手动创建约束？

Answer 1

您的代码可以大量使用Visual Format Language更紧凑：

let newView = UIView() 
newView.backgroundColor = UIColor.redColor() 
newView.translatesAutoresizingMaskIntoConstraints = false 
view.addSubview(newView) 

let disableButton = UIButton() 
disableButton.backgroundColor = UIColor.blueColor() 
disableButton.translatesAutoresizingMaskIntoConstraints = false 
view.addSubview(disableButton) 

let views = ["newView": newView, "disableButton": disableButton] 
let c1 = NSLayoutConstraint.constraintsWithVisualFormat("V:|[newView]|", options: [], metrics: nil, views: views) 
let c2 = NSLayoutConstraint.constraintsWithVisualFormat("H:|[newView]|", options: [], metrics: nil, views: views) 
let c3 = NSLayoutConstraint.constraintsWithVisualFormat("V:|[disableButton]|", options: [], metrics: nil, views: views) 
let c4 = NSLayoutConstraint.constraintsWithVisualFormat("H:|-0-[disableButton]", options: [], metrics: nil, views: views) 
let c5 = NSLayoutConstraint(item: disableButton, attribute: .Width, relatedBy: .Equal, toItem: newView, attribute: .Width, multiplier: 0.75, constant: 0) 

NSLayoutConstraint.activateConstraints(c1 + c2 + c3 + c4) 
view.addConstraint(c5) 

• c1告诉自动布局，使红色视图填补了上海华垂直。
• c2做同样的水平
• c3告诉自动布局，使蓝色按钮填写垂直
• c4使得它粘到屏幕的左边
• c5：一些约束不能用视觉形式写语言，因此我们需要使用不同的功能，使disableButton.width = newView.width * 0.75

我可以写的最后一行的

NSLayoutConstraint.activateConstraints(c1 + c2 + c3 + c4 + [c5]) 

但由于某些原因，这需要很长时间才能编译。因此，你在上面的代码中看到了分割。