在Swift中子类化NSLayoutConstraint
我想在Swift中对在Swift中子类化NSLayoutConstraint,swift,inheritance,nslayoutconstraint,subclassing,Swift,Inheritance,Nslayoutconstraint,Subclassing,我想在Swift中对NSLayoutConstraint进行子类化,以便为实例化常见约束提供更简单的方法(例如height,width,…) 到目前为止,我编写的代码草稿无法正常工作,因为编写时无法访问项-属性: class TestConstraint: NSLayoutConstraint { init(item: Any) { super.init() self.firstItem = item // WARNING: Cannot assign t
NSLayoutConstraint
进行子类化,以便为实例化常见约束提供更简单的方法(例如height
,width
,…)
到目前为止,我编写的代码草稿无法正常工作,因为编写时无法访问项
-属性:
class TestConstraint: NSLayoutConstraint {
init(item: Any) {
super.init()
self.firstItem = item // WARNING: Cannot assign to property: 'firstItem' is a get-only property
// ...
}
}
是否可以用这种方式将
NSLayoutConstraint
子类化,或者我需要额外考虑其他事项?我认为您需要的是UIView的扩展
extension UIView{
func anchor(top:NSLayoutYAxisAnchor?,leading:NSLayoutXAxisAnchor?,trailing:NSLayoutXAxisAnchor?,bottom:NSLayoutYAxisAnchor?,padding:UIEdgeInsets = .zero,size:CGSize = .zero){
translatesAutoresizingMaskIntoConstraints = false
if let top = top{
topAnchor.constraint(equalTo: top, constant: padding.top).isActive = true
}
if let leading = leading{
leadingAnchor.constraint(equalTo: leading, constant: padding.left).isActive = true
}
if let trailing = trailing{
trailingAnchor.constraint(equalTo: trailing, constant: -padding.right).isActive = true
}
if let bottom = bottom{
bottomAnchor.constraint(equalTo: bottom, constant: -padding.bottom).isActive = true
}
if size.width != 0{
widthAnchor.constraint(equalToConstant: size.width).isActive = true
}
if size.height != 0{
heightAnchor.constraint(equalToConstant: size.height).isActive = true
}
}
}
你试过布局锚吗?。这是首选的方式。不要将其子类化这更简单,谢谢。如果您真的想自定义约束,