由于XCode认为纵向模式下的iPhone 5和iPhone XS高度都是常规的,因此我试图处理不同iPhone(纵向模式)的视图高度。
为此,我尝试了两种方法:
1)继承NSLayoutConstraint:
@IBDesignable class AdaptiveConstraint: NSLayoutConstraint {
@IBInspelctable override var constant: CGFloat {
get { return self.constant }
set { self.constant = newValue + A_VARIABLE_I_USE_BASED_ON_IPHONE_TYPE }}}
2)继承UIView:
@IBDesignable class AttributedView: UIView {
@IBInspectable var height: CGFloat {
get {
return self.heightAnchor.constraint(equalToConstant: self.bounds.height).constant
}
set {
self.heightAnchor.constraint(equalToConstant: self.bounds.height).constant = newValue + A_VARIABLE_I_USE_BASED_ON_IPHONE_TYPE
}}}
第一个在设置器上崩溃,第二个没有影响。 我将不胜感激任何建议。 预先谢谢你!
答案 0 :(得分:2)
第一个需要以下格式:
override var constant: CGFloat {
get {
// note we are calling `super.`, added subtract for consistency
return super.constant - A_VARIABLE_I_USE_BASED_ON_IPHONE_TYPE
}
set {
// note we are calling `super.`
super.constant = newValue + A_VARIABLE_I_USE_BASED_ON_IPHONE_TYPE
}
}
第二个在您每次调用它时都会创建一个新的约束。约束不会添加到视图层次结构,也不会激活。立即发布。
它需要以下格式:
// it would be better to create and add it in viewDidLoad though
lazy var heightConstraint: NSLayoutConstraint = {
let constraint = self.heightAnchor.constraint(equalToConstant: self.bounds.height)
constraint.isActive = true
return constraint
}()
@IBInspectable var height: CGFloat {
get {
return self.heightConstraint.constant - A_VARIABLE_I_USE_BASED_ON_IPHONE_TYPE
}
set {
self.heightConstraint.constant = newValue + A_VARIABLE_I_USE_BASED_ON_IPHONE_TYPE
}
}