[英]Can't set UIView's background color Swift 5
我有一個視圖,我像這樣初始化:
var view: UIView! = {
var perm = UIView()
perm.backgroundColor = UIColor.black
// enable auto layout
perm.translatesAutoresizingMaskIntoConstraints = false
return perm
}()
之后,我添加一個標簽作為子視圖來view
。 標簽初始化如下:
var title: UILabel! = {
let perm = UILabel()
perm.textColor = UIColor.white
perm.numberOfLines = 0
perm.font = UIFont.boldSystemFont(ofSize: 20)
// enable auto layout
perm.translatesAutoresizingMaskIntoConstraints = false
return perm
}()
之后,我以編程方式添加了一些約束。 當我運行應用程序時, title
顯示在正確的位置,但尚未設置view
的背景顏色。
編輯
這就是我設置約束的方式:
view.addSubview(title)
view.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true
view.trailingAnchor.constraint(equalTo: trailingAnchor).isActive = true
view.bottomAnchor.constraint(equalTo: image.bottomAnchor).isActive = true
title.leadingAnchor.constraint(equalTo: title.superview!.leadingAnchor, constant: 20).isActive = true
title.trailingAnchor.constraint(equalTo: title.superview!.trailingAnchor, constant: -20).isActive = true
title.bottomAnchor.constraint(equalTo: title.superview!.bottomAnchor, constant: -20).isActive = true
view
需要高度
view.heightAnchor.constraint(equalToConstant:200).isActive = true
或對於標簽高度加上頂部和底部填充 40
title.topAnchor.constraint(equalTo:view.topAnchor, constant:20).isActive = true
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