[英]Auto set height of container view based on subviews
I know this question has been asked numerous times, but I can't quite seem to get to the bottom of this problem. 我知道这个问题已经被问过无数次了,但是我似乎不太了解这个问题的根源。
Using Auto Layout, I would like to automatically set the height of my container UIView based on its subviews. 使用自动布局,我想基于其子视图自动设置容器UIView的高度。 I have looked at using sizeToFit
and other various methods of summing up the height of my subviews, however from what I've read the height of my container height should be automatic when using Auto Layout because of the subviews "intrinsic" content size. 我已经看过使用sizeToFit
和其他各种方法来汇总子视图的高度,但是根据我的了解,使用自动布局时,由于子视图的“内在”内容大小,容器高度应该是自动的。
Below is a reduced case of what I'm experiencing. 以下是我所遇到的情况的简化案例。 I would really appreciate any guidance! 我真的很感谢任何指导!
Overview: 概述:
Code: 码:
class ViewController: UIViewController {
let redView = RedView()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(redView)
view.setNeedsUpdateConstraints()
}
}
class RedView: UIView {
let greenView = GreenView()
let blueView = BlueView()
init() {
super.init(frame: CGRect.zero)
translatesAutoresizingMaskIntoConstraints = false
backgroundColor = UIColor.red()
addSubview(greenView)
addSubview(blueView)
setNeedsUpdateConstraints()
}
override func updateConstraints() {
super.updateConstraints()
NSLayoutConstraint(item: greenView, attribute: .top, relatedBy: .equal, toItem: self, attribute: .top, multiplier: 1, constant: 0).isActive = true
NSLayoutConstraint(item: blueView, attribute: .top, relatedBy: .equal, toItem: greenView, attribute: .bottom, multiplier: 1, constant: 0).isActive = true
NSLayoutConstraint(item: self, attribute: .left, relatedBy: .equal, toItem: superview, attribute: .left, multiplier: 1, constant: 0).isActive = true
NSLayoutConstraint(item: self, attribute: .right, relatedBy: .equal, toItem: superview, attribute: .right, multiplier: 1, constant: 0).isActive = true
NSLayoutConstraint(item: self, attribute: .centerY, relatedBy: .equal, toItem: superview, attribute: .centerY, multiplier: 1, constant: 0).isActive = true
NSLayoutConstraint(item: self, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 200).isActive = true
}
}
class GreenView: UIView {
init() {
super.init(frame: CGRect.zero)
translatesAutoresizingMaskIntoConstraints = false
backgroundColor = UIColor.green()
}
override func updateConstraints() {
super.updateConstraints()
NSLayoutConstraint(item: self, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 300).isActive = true
NSLayoutConstraint(item: self, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 100).isActive = true
NSLayoutConstraint(item: self, attribute: .centerX, relatedBy: .equal, toItem: superview, attribute: .centerX, multiplier: 1, constant: 0).isActive = true
}
}
class BlueView: UIView {
init() {
super.init(frame: CGRect.zero)
translatesAutoresizingMaskIntoConstraints = false
backgroundColor = UIColor.blue()
}
override func updateConstraints() {
super.updateConstraints()
NSLayoutConstraint(item: self, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 300).isActive = true
NSLayoutConstraint(item: self, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 100).isActive = true
NSLayoutConstraint(item: self, attribute: .centerX, relatedBy: .equal, toItem: superview, attribute: .centerX, multiplier: 1, constant: 0).isActive = true
}
}
您需要将blueView的底部固定到redView的底部,只需将此行添加到redView的updateConstraints
:
NSLayoutConstraint(item: blueView, attribute: .bottom, relatedBy: .equal, toItem: self, attribute: .bottom, multiplier: 1, constant: 0).active = true
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