使用自動佈局,你的優勢。它可以爲你完成所有繁重的工作。
這是一個UIViewController
,它列出了3 UILabels
,就像你在屏幕截圖中一樣,沒有任何計算。有3 UIView
子視圖用於給標籤「填充」並設置背景顏色。其中每個UIViews
都有一個UILabel
子視圖,它只顯示文本而沒有其他內容。
所有的佈局都在viewDidLoad
的自動佈局中完成,這意味着沒有計算比率或幀,也沒有KVO。改變諸如填充和壓縮/擁抱優先級之類的事情是輕而易舉的。這也可能避免依賴像TZStackView
這樣的開源解決方案。這與在界面生成器中完全一樣簡單,完全不需要代碼。
class StackViewController: UIViewController {
private let leftView: UIView = {
let leftView = UIView()
leftView.translatesAutoresizingMaskIntoConstraints = false
leftView.backgroundColor = .blueColor()
return leftView
}()
private let leftLabel: UILabel = {
let leftLabel = UILabel()
leftLabel.translatesAutoresizingMaskIntoConstraints = false
leftLabel.textColor = .whiteColor()
leftLabel.text = "A medium title"
leftLabel.textAlignment = .Center
return leftLabel
}()
private let middleView: UIView = {
let middleView = UIView()
middleView.translatesAutoresizingMaskIntoConstraints = false
middleView.backgroundColor = .redColor()
return middleView
}()
private let middleLabel: UILabel = {
let middleLabel = UILabel()
middleLabel.translatesAutoresizingMaskIntoConstraints = false
middleLabel.textColor = .whiteColor()
middleLabel.text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit"
middleLabel.textAlignment = .Center
return middleLabel
}()
private let rightView: UIView = {
let rightView = UIView()
rightView.translatesAutoresizingMaskIntoConstraints = false
rightView.backgroundColor = .greenColor()
return rightView
}()
private let rightLabel: UILabel = {
let rightLabel = UILabel()
rightLabel.translatesAutoresizingMaskIntoConstraints = false
rightLabel.textColor = .whiteColor()
rightLabel.text = "OK"
rightLabel.textAlignment = .Center
return rightLabel
}()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(leftView)
view.addSubview(middleView)
view.addSubview(rightView)
leftView.addSubview(leftLabel)
middleView.addSubview(middleLabel)
rightView.addSubview(rightLabel)
let views: [String : AnyObject] = [
"topLayoutGuide" : topLayoutGuide,
"leftView" : leftView,
"leftLabel" : leftLabel,
"middleView" : middleView,
"middleLabel" : middleLabel,
"rightView" : rightView,
"rightLabel" : rightLabel
]
// Horizontal padding for UILabels inside their respective UIViews
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-(16)-[leftLabel]-(16)-|", options: [], metrics: nil, views: views))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-(16)-[middleLabel]-(16)-|", options: [], metrics: nil, views: views))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-(16)-[rightLabel]-(16)-|", options: [], metrics: nil, views: views))
// Vertical padding for UILabels inside their respective UIViews
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-(6)-[leftLabel]-(6)-|", options: [], metrics: nil, views: views))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-(6)-[middleLabel]-(6)-|", options: [], metrics: nil, views: views))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-(6)-[rightLabel]-(6)-|", options: [], metrics: nil, views: views))
// Set the views' vertical position. The height can be determined from the label's intrinsic content size, so you only need to specify a y position to layout from. In this case, we specified the top of the screen.
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:[topLayoutGuide][leftView]", options: [], metrics: nil, views: views))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:[topLayoutGuide][middleView]", options: [], metrics: nil, views: views))
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:[topLayoutGuide][rightView]", options: [], metrics: nil, views: views))
// Horizontal layout of views
NSLayoutConstraint.activateConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[leftView][middleView][rightView]|", options: [], metrics: nil, views: views))
// Make sure the middle view is the view that expands to fill up the extra space
middleLabel.setContentHuggingPriority(UILayoutPriorityDefaultLow, forAxis: .Horizontal)
middleView.setContentHuggingPriority(UILayoutPriorityDefaultLow, forAxis: .Horizontal)
}
}
結果視圖: