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[英]How do I programatically resize a UIButton that already has constraints?
[英]If I want to create these constraints programatically, how do I do so?
您可以使用視覺格式語言來相對容易地做到這一點:
將視圖, topLayoutGuide
和bottomLayoutGuide
添加到字典中。 我用過views
。 您還必須將translatesAutoresizingMaskIntoConstraints
設置為false
,約束才能起作用。
例:
view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[yourView]-(-15)-|", options: [], metrics: nil, views: views))
view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:[topLayout][yourView][botLayout]", options: [], metrics: nil, views: views))
一種方法是:
let newView = UIView()
newView.backgroundColor = UIColor.redColor()
newView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(newView)
let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Leading, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Leading, multiplier: 1, constant: 0)
view.addConstraint(horizontalConstraint)
let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Trailing, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Trailing, multiplier: 1, constant: -15)
view.addConstraint(verticalConstraint)
let widthConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Top, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.Top, multiplier: 1, constant: 0)
view.addConstraint(widthConstraint)
let heightConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Bottom, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.Bottom, multiplier: 1, constant: 0)
view.addConstraint(heightConstraint)
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