简单的 UIStackView 打破了限制

Question

我在 UIViewRepresentable 中有一个 UIStackView，但我无法让它在没有约束错误的情况下工作。

这是错误：

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. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x6000028edf40 h=--& v=--& benjamin_ios.ConversationChatViewWithSendMessage:0x7fef7323a610.height == 0   (active)>",
    "<NSLayoutConstraint:0x600002893c00 UIView:0x7fef7322a3d0.height == 100   (active)>",
    "<NSLayoutConstraint:0x600002891d10 V:|-(0)-[UIStackView:0x7fef7320c450]   (active, names: '|':benjamin_ios.ConversationChatViewWithSendMessage:0x7fef7323a610 )>",
    "<NSLayoutConstraint:0x600002891c70 UIStackView:0x7fef7320c450.bottom == benjamin_ios.ConversationChatViewWithSendMessage:0x7fef7323a610.bottom   (active)>",
    "<NSLayoutConstraint:0x6000028e6170 'UISV-canvas-connection' UIStackView:0x7fef7320c450.top == UIView:0x7fef73229830.top   (active)>",
    "<NSLayoutConstraint:0x6000028e4050 'UISV-canvas-connection' V:[UIView:0x7fef7322a3d0]-(0)-|   (active, names: '|':UIStackView:0x7fef7320c450 )>",
    "<NSLayoutConstraint:0x6000028ecc30 'UISV-spacing' V:[UIView:0x7fef73229830]-(0)-[UIView:0x7fef7322a3d0]   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x600002893c00 UIView:0x7fef7322a3d0.height == 100   (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.

这是代码：

struct ConversationChatMessagesWrapper: UIViewRepresentable {
    private let view = ConversationChatViewWithSendMessage()

    func makeUIView(context _: Context) -> ConversationChatViewWithSendMessage {
        view
    }

    func updateUIView(
        _: ConversationChatViewWithSendMessage,
        context _: Context
    ) {}
}


class ConversationChatViewWithSendMessage: UIView {
    @available(*, unavailable)
    required init?(coder _: NSCoder) {
        fatalError("Not used")
    }

    init() {
        super.init(frame: .zero)

        backgroundColor = .red

        let otherView = UIView()

        otherView.backgroundColor = .blue
        otherView.translatesAutoresizingMaskIntoConstraints = false

        let otherView2 = UIView()

        otherView2.backgroundColor = .brown
        otherView2.translatesAutoresizingMaskIntoConstraints = false

        let stack = UIStackView(arrangedSubviews: [otherView, otherView2])

        stack.translatesAutoresizingMaskIntoConstraints = false
        stack.axis = .vertical
        stack.distribution = .fill
        stack.alignment = .fill

        addSubview(stack)

        stack.topAnchor.constraint(equalTo: topAnchor).isActive = true
        stack.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
        stack.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true
        stack.trailingAnchor.constraint(equalTo: trailingAnchor).isActive = true

        otherView2.heightAnchor.constraint(equalToConstant: 100).isActive = true
    }
}

这是我想要实现的目标（显示实际上是我想要的，但我想摆脱约束错误）：

Answer 1

解决方案是为我创建的所有约束赋予defaultHigh优先级。这与 SwiftUI 移植到 UIKit 相关，因为代码在普通 UIKit 中运行良好。