ios - Swift UIView Constraint Constant Height Changing时间获取LayoutConstraints警告

Question

我的场景，我在 storyboard 中实现了 UIView，高度恒定为 90。在这个 UIView 中，我有两个 UIView height 25 和另一个 UICollectionView 54。现在，我试图以编程方式将基本 UIView 高度从 90 降低到 35，但我收到了 LayoutConstraints 警告。为正确的方法提供一些解决方案。

下面是我正在使用的代码

BottomGalleryHeight.constant = 90 // Changing to 35
photoGalleryView.layoutIfNeeded()

我的警告错误

[LayoutConstraints] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x282679360 UIView:0x102f30880.height == 25   (active)>",
    "<NSLayoutConstraint:0x282679450 UIView:0x102f306a0.height == 35   (active)>",
    "<NSLayoutConstraint:0x2826794a0 V:|-(0)-[UIView:0x102f30880]   (active, names: '|':UIView:0x102f306a0 )>",
    "<NSLayoutConstraint:0x28267e210 V:[UIView:0x102f30880]-(10)-[UICollectionView:0x10385e000]   (active)>",
    "<NSLayoutConstraint:0x28267d450 V:[UICollectionView:0x10385e000]-(1)-|   (active, names: '|':UIView:0x102f306a0 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x282679360 UIView:0x102f30880.height == 25   (active)>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.

Answer 1

这里是你如何让它工作，

class VC: UIViewController {
    @IBOutlet weak var outerViewHeight: NSLayoutConstraint!
    @IBOutlet weak var innerViewHeight: NSLayoutConstraint!
    @IBOutlet weak var collectionViewHeight: NSLayoutConstraint!

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    @IBAction func onTapButton(_ sender: UIButton) {
        outerViewHeight.constant = 35.0
        innerViewHeight.constant = 10.0
        collectionViewHeight.constant = 25.0

        UIView.animate(withDuration: 0.3) {
            self.view.layoutIfNeeded()
        }
    }
}