【发布时间】：2018-12-11 23:34:25
【问题描述】：
我正在从viewWillAppear 的笔尖加载自定义视图类。加载笔尖后，我将其添加为子视图，然后应用一些约束，然后更新约束。那时我尝试向这个视图添加阴影，但没有显示阴影....
仅在某些情况下，ViewController 具有包含contentView 的滚动视图。所有视图的内容都在这个contentView 中。
这是我的代码：
视图控制器
class MyViewController: UIViewController {
@IBOutlet weak var contentView: UIView!
var matches: [Match] = []
var matchViews: [MatchDetailsView] = []
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
setMatches()
}
func setMatches() {
// Match One
let matchOneDetailsView = MatchDetailsView.instanceFromNib(match: matches.count > 0 ? matches[0] : nil, delegate: self, tag: 1)
contentView.addSubview(matchOneDetailsView)
matchOneDetailsView.translatesAutoresizingMaskIntoConstraints = false
let matchOneLeadingConstraint = NSLayoutConstraint(item: matchOneDetailsView, attribute: .leading, relatedBy: .equal, toItem: contentView, attribute: .leading, multiplier: 1, constant: 16)
let matchOneTrailingConstraint = NSLayoutConstraint(item: matchOneDetailsView, attribute: .trailing, relatedBy: .equal, toItem: contentView, attribute: .trailing, multiplier: 1, constant: -16)
let matchOneTopConstraint = NSLayoutConstraint(item: matchOneDetailsView, attribute: .top, relatedBy: .equal, toItem: contentView, attribute: .top, multiplier: 1, constant: 32)
// Match Two
let matchTwoDetailsView = MatchDetailsView.instanceFromNib(match: matches.count > 1 ? matches[1] : nil, delegate: self, tag: 2)
contentView.addSubview(matchTwoDetailsView)
matchTwoDetailsView.translatesAutoresizingMaskIntoConstraints = false
let matchTwoLeadingConstraint = NSLayoutConstraint(item: matchTwoDetailsView, attribute: .leading, relatedBy: .equal, toItem: contentView, attribute: .leading, multiplier: 1, constant: 16)
let matchTwoTrailingConstraint = NSLayoutConstraint(item: matchTwoDetailsView, attribute: .trailing, relatedBy: .equal, toItem: contentView, attribute: .trailing, multiplier: 1, constant: -16)
let matchTwoTopConstraint = NSLayoutConstraint(item: matchTwoDetailsView, attribute: .top, relatedBy: .equal, toItem: matchOneDetailsView, attribute: .bottom, multiplier: 1, constant: 32)
// Match Three
let matchThreeDetailsView = MatchDetailsView.instanceFromNib(match: matches.count > 2 ? matches[2] : nil, delegate: self, tag: 3)
contentView.addSubview(matchThreeDetailsView)
matchThreeDetailsView.translatesAutoresizingMaskIntoConstraints = false
let matchThreeLeadingConstraint = NSLayoutConstraint(item: matchThreeDetailsView, attribute: .leading, relatedBy: .equal, toItem: contentView, attribute: .leading, multiplier: 1, constant: 16)
let matchThreeTrailingConstraint = NSLayoutConstraint(item: matchThreeDetailsView, attribute: .trailing, relatedBy: .equal, toItem: contentView, attribute: .trailing, multiplier: 1, constant: -16)
let matchThreeTopConstraint = NSLayoutConstraint(item: matchThreeDetailsView, attribute: .top, relatedBy: .equal, toItem: matchTwoDetailsView, attribute: .bottom, multiplier: 1, constant: 32)
let matchThreeBottomConstraint = NSLayoutConstraint(item: matchThreeDetailsView, attribute: .bottom, relatedBy: .equal, toItem: contentView, attribute: .bottom, multiplier: 1, constant: -32)
NSLayoutConstraint.activate([matchOneLeadingConstraint, matchOneTrailingConstraint, matchOneTopConstraint, matchTwoLeadingConstraint, matchTwoTrailingConstraint, matchTwoTopConstraint, matchThreeLeadingConstraint, matchThreeTrailingConstraint, matchThreeTopConstraint, matchThreeBottomConstraint])
updateViewConstraints()
matchViews.append(matchOneDetailsView)
matchViews.append(matchTwoDetailsView)
matchViews.append(matchThreeDetailsView)
styleMatchViews()
}
func styleMatchViews() {
for view in matchViews {
view.addShadow(opacity: 0.25, yOffset: 0, xOffset: 0, radius: 5.0)
view.roundCorners(withRadius: 5.0)
}
}
}
MatchDetailsView
class MatchDetailsView: UIView {
class func instanceFromNib(match: Match?, delegate: MatchDetailsViewDelegate, tag: Int) -> MatchDetailsView {
let view = UINib(nibName: "MatchDetailsView", bundle: nil).instantiate(withOwner: MatchDetailsView(), options: nil)[0] as! MatchDetailsView
view.translatesAutoresizingMaskIntoConstraints = false
view.updateMatchContent()
return view
}
}
UIViewExtension
extension UIView {
/**
Add Shadow
Puts a Drop Shadow in the UIView
*/
func addShadow(opacity: Float, yOffset: Int, xOffset: Int, radius: CGFloat) {
self.layer.masksToBounds = false
self.layer.shadowColor = UIColor.black.cgColor
self.layer.shadowOpacity = opacity
self.layer.shadowOffset = CGSize(width: xOffset, height: yOffset)
self.layer.shadowRadius = radius
self.layer.shadowPath = UIBezierPath(rect: self.bounds).cgPath
}
}
如果MatchDetailsView 的 nib 文件将“clipsToBounds”设置为 false，为什么加载页面时我的影子没有出现？我是否错过了 layout 函数，即使它们的布局似乎正确？
【问题讨论】：
标签： ios swift uiview nslayoutconstraint