我添加了以下代码来使以编程方式添加的 View 居中:
let horizontalConstraint = NSLayoutConstraint(item: newView!, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 0)
view.addConstraint(horizontalConstraint)
这是行不通的。 View 不居中。它仍然在左边。
编辑:
override func viewDidLoad() {
super.viewDidLoad()
newView = LineChartView(frame: CGRectMake(0, 0, 50, 50))
newView?.delegate = self
newView?.drawBordersEnabled = true
newView?.noDataText = "No Data"
newView?.noDataTextDescription = "No Data"
newView?.borderColor = UIColor.blackColor()
self.view.addSubview(newView!)
最佳答案
friend ,你需要选择一方,如果你使用自动布局,不要用frame
初始化你的对象。尝试这样的事情......
var newView:LineChartView!
override func viewDidLoad() {
super.viewDidLoad()
newView = LineChartView()
newView.translatesAutoresizingMaskIntoConstraints = false
newView.delegate = self
newView.drawBordersEnabled = true
newView.noDataText = "No Data"
newView.noDataTextDescription = "No Data"
newView.borderColor = UIColor.blackColor()
self.view.addSubview(newView)
let width = NSLayoutConstraint(item: newView, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 50)
let height = NSLayoutConstraint(item: newView, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 50)
newView.addConstraint(width)
newView.addConstraint(height)
let x = NSLayoutConstraint(item: newView, attribute: .CenterX, relatedBy: .Equal, toItem: self.view, attribute: .CenterX, multiplier: 1, constant: 0)
let y = NSLayoutConstraint(item: newView, attribute: .CenterY, relatedBy: .Equal, toItem: self.view, attribute: .CenterY, multiplier: 1, constant: 0)
self.view.addConstraint(x)
self.view.addConstraint(y)
}
如果您的 LineChartView
对象是 UIView
的子类,那么这应该有效,并且您的 super View 中间应该有一个 50x50 的对象。
如果您要在代码中进行这样的约束,您应该考虑使用 Apples Visual Formatting Language .
关于ios - 在 Swift 中以编程方式添加约束不起作用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/34331622/