ios - 如何解决: Unable to simultaneously satisfy constraints

Question

我想这样创作(通过 Storyboard完成)

这是通过 Storyboard完成的。根据我的观察，我发现约束问题是由 "totalAmountImg" 引起的。我不更改所有对象的优先级属性(所有对象的优先级 == 1000)

这是结果。 (SummaryVC - 以编程方式完成)

注意:我想让 SummaryVC totalAmountImg(以编程方式)看起来像上图(由 Storyboard制作)

totalAmountImg 的 Storyboard 限制

这正是我通过代码创建的。但是我不知道为什么会弹出这个错误。

totalImgConstraint

func totalAmountImgConstraints() {
        let imgCenterY = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .centerY,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .centerY,
                           multiplier: 1.0,
                           constant: 0)
        imgCenterY.identifier = "imgCenterY"
        imgCenterY.isActive = true

        let imgRight = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .right,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .right,
                           multiplier: 1.0,
                           constant: 16)
        imgRight.identifier = "imgRight"
        imgRight.isActive = true

        let imgAspectRatio = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .height,
                           relatedBy: .equal,
                           toItem: totalAmountImg,
                           attribute: .width,
                           multiplier: 1.0 / 1.0,
                           constant: 0)
        imgAspectRatio.identifier = "imgAspectRatio"
        imgAspectRatio.isActive = true

        let imgLeft = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .left,
                           relatedBy: .equal,
                           toItem: totalPriceLbl,
                           attribute: .right,
                           multiplier: 1.0,
                           constant: 4)
        imgLeft.identifier = "imgLeft"
        imgLeft.isActive = true

        let imgWidth = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .width,
                           relatedBy: .lessThanOrEqual,
                           toItem: totalAmountView,
                           attribute: .width,
                           multiplier: 0.2,
                           constant: 0)
        imgWidth.identifier = "imgWidth"
        imgWidth.isActive = true
    }

总结VC

class SummaryVC: UIViewController, UIScrollViewDelegate {

    @IBOutlet weak var scrollView: UIScrollView!
    @IBOutlet weak var pageController: UIPageControl!

    let numberOfPages = 3

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

        // Add subViews
        scrollView.addSubview(summaryBaseView)
        scrollView.addSubview(paymentTypeBaseView)
        scrollView.addSubview(itemNameBaseView)

        summaryBaseView.addSubview(totalAmountView)
        summaryBaseView.addSubview(runningTableView)
        summaryBaseView.addSubview(partnerAmountView)

        totalAmountView.addSubview(totalLbl)
        totalAmountView.addSubview(totalPriceLbl)
        totalAmountView.addSubview(totalAmountImg)


        view.setNeedsUpdateConstraints()

        // set content size
        scrollView.contentSize = CGSize(width: scrollView.frame.width * CGFloat(numberOfPages), height: scrollView.frame.height)
    }

    override func viewDidLayoutSubviews() {

    }

    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        let pageNumber = scrollView.contentOffset.x / scrollView.frame.width
        pageController.currentPage = Int(pageNumber)
        pageController.currentPageIndicatorTintColor = UIColor.white
    }

    //-----------------------------------------------------------------
    // MARK: - Methods
    //-----------------------------------------------------------------

    func basicDesignSetup() {
        pageController.numberOfPages = numberOfPages
        let scrollViewSize = scrollView.frame.size
        let scrollViewWidth = scrollView.frame.width

        // Summary View
        let summeryOrigin = CGPoint(x: 0, y: 0)
        summaryBaseView = UIView(frame: CGRect(origin: summeryOrigin, size: scrollViewSize))
        summaryBaseView.backgroundColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1)

        // Payment Type View
        let paymentTypeOrigin = CGPoint(x: scrollViewWidth, y: 0)
        paymentTypeBaseView = UIView(frame: CGRect(origin: paymentTypeOrigin, size: scrollViewSize))
        paymentTypeBaseView.backgroundColor = #colorLiteral(red: 0.01680417731, green: 0.1983509958, blue: 1, alpha: 1)

        // Item Name View
        let itemNameOrigin = CGPoint(x: scrollViewWidth * 2, y: 0)
        itemNameBaseView = UIView(frame: CGRect(origin: itemNameOrigin, size: scrollViewSize))
        itemNameBaseView.backgroundColor = #colorLiteral(red: 0, green: 0.9914394021, blue: 1, alpha: 1)

        // Total Amount View
        totalAmountView.backgroundColor = #colorLiteral(red: 0.5480614305, green: 0.8129847646, blue: 0.6160266995, alpha: 1)
        runningTableView.backgroundColor = #colorLiteral(red: 0.4280827343, green: 0.7700845003, blue: 0.9571052194, alpha: 1)
        partnerAmountView.backgroundColor = #colorLiteral(red: 0.9137254902, green: 0.4470588235, blue: 0.4549019608, alpha: 1)

        totalLbl.text = "Total Amount"
        totalLbl.textColor = #colorLiteral(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)
        totalLbl.backgroundColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1)
        totalLbl.font = UIFont.systemFont(ofSize: 16, weight: .medium)

        totalPriceLbl.text = "5532.00"
        totalPriceLbl.textColor = #colorLiteral(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)
        totalPriceLbl.backgroundColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1)

        totalAmountImg.contentMode = .scaleAspectFit
        totalAmountImg.image = #imageLiteral(resourceName: "tick")
        totalAmountImg.backgroundColor = #colorLiteral(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)

    }


    //-----------------------------------------------------------------
    // MARK: - Views - programatically
    //-----------------------------------------------------------------

    // Base Views
    lazy var summaryBaseView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()

    lazy var paymentTypeBaseView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()

    lazy var itemNameBaseView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()

    // $$$$$ Summary Sub Views $$$$$

    // Total Amount
    lazy var totalAmountView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()

    lazy var totalLbl: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

    lazy var totalPriceLbl: UnderlinedLabel = {
        let label = UnderlinedLabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

    lazy var totalAmountImg: UIImageView = {
        let imageView = UIImageView()
        imageView.translatesAutoresizingMaskIntoConstraints = false
        return imageView
    }()

    // Running Table
    lazy var runningTableView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()

    lazy var runningLbl: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

    lazy var runningPriceLbl: UnderlinedLabel = {
        let label = UnderlinedLabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

    lazy var runningTableImg: UIImageView = {
        let imageView = UIImageView()
        imageView.translatesAutoresizingMaskIntoConstraints = false
        return imageView
    }()

    // Partner Amount
    lazy var partnerAmountView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()

    lazy var partnerLbl: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

    lazy var partnerPriceLbl: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

    lazy var partnerAmountImg: UIImageView = {
        let imageView = UIImageView()
        imageView.translatesAutoresizingMaskIntoConstraints = false
        return imageView
    }()



    //-----------------------------------------------------------------
    // MARK: - Constraints
    //-----------------------------------------------------------------

    override func updateViewConstraints() {
        totalAmountViewConstraints()
        runningTableViewConstraints()
        partnerAmountViewConstraints()

        // Total Amount View
        totalLblConstraint()
        totalPriceLblConstraints()
        totalAmountImgConstraints()

        super.updateViewConstraints()
    }

    func totalAmountViewConstraints() {
        NSLayoutConstraint(item: totalAmountView,
                           attribute: .left,
                           relatedBy: .equal,
                           toItem: summaryBaseView,
                           attribute: .left,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalAmountView,
                           attribute: .right,
                           relatedBy: .equal,
                           toItem: summaryBaseView,
                           attribute: .right,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalAmountView,
                           attribute: .top,
                           relatedBy: .equal,
                           toItem: summaryBaseView,
                           attribute: .top,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalAmountView,
                           attribute: .bottom,
                           relatedBy: .equal,
                           toItem: runningTableView,
                           attribute: .top,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalAmountView,
                           attribute: .height,
                           relatedBy: .equal,
                           toItem: runningTableView,
                           attribute: .height,
                           multiplier: 1.0,
                           constant: 0).isActive = true
    }

    func runningTableViewConstraints() {
        NSLayoutConstraint(item: runningTableView,
                           attribute: .leading,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .leading,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: runningTableView,
                           attribute: .trailing,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .trailing,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: runningTableView,
                           attribute: .top,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .bottom,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: runningTableView,
                           attribute: .bottom,
                           relatedBy: .equal,
                           toItem: partnerAmountView,
                           attribute: .top,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: runningTableView,
                           attribute: .height,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .height,
                           multiplier: 1.0,
                           constant: 0).isActive = true
    }

    func partnerAmountViewConstraints() {
        NSLayoutConstraint(item: partnerAmountView,
                           attribute: .leading,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .leading,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: partnerAmountView,
                           attribute: .trailing,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .trailing,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: partnerAmountView,
                           attribute: .top,
                           relatedBy: .equal,
                           toItem: runningTableView,
                           attribute: .bottom,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: partnerAmountView,
                           attribute: .bottom,
                           relatedBy: .equal,
                           toItem: summaryBaseView,
                           attribute: .bottom,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: partnerAmountView,
                           attribute: .height,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .height,
                           multiplier: 1.0,
                           constant: 0).isActive = true
    }

    // Total Ammount Section Subviews
    func totalLblConstraint() {
        NSLayoutConstraint(item: totalLbl,
                           attribute: .top,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .top,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalLbl,
                           attribute: .left,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .left,
                           multiplier: 1.0,
                           constant: 16).isActive = true

        NSLayoutConstraint(item: totalLbl,
                           attribute: .bottom,
                           relatedBy: .equal,
                           toItem: totalPriceLbl,
                           attribute: .top,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalLbl,
                           attribute: .height,
                           relatedBy: .equal,
                           toItem: totalPriceLbl,
                           attribute: .height,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalLbl,
                           attribute: .width,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .width,
                           multiplier: 0.7,
                           constant: 0).isActive = true
    }

    func totalPriceLblConstraints() {
        NSLayoutConstraint(item: totalPriceLbl,
                           attribute: .top,
                           relatedBy: .equal,
                           toItem: totalLbl,
                           attribute: .bottom,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalPriceLbl,
                           attribute: .leading,
                           relatedBy: .equal,
                           toItem: totalLbl,
                           attribute: .leading,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalPriceLbl,
                           attribute: .bottom,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .bottom,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalPriceLbl,
                           attribute: .height,
                           relatedBy: .equal,
                           toItem: totalLbl,
                           attribute: .height,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalPriceLbl,
                           attribute: .width,
                           relatedBy: .equal,
                           toItem: totalLbl,
                           attribute: .width,
                           multiplier: 1.0,
                           constant: 0).isActive = true

        NSLayoutConstraint(item: totalPriceLbl,
                           attribute: .trailing,
                           relatedBy: .equal,
                           toItem: totalLbl,
                           attribute: .trailing,
                           multiplier: 1.0,
                           constant: 0).isActive = true
    }

    func totalAmountImgConstraints() {
        let imgCenterY = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .centerY,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .centerY,
                           multiplier: 1.0,
                           constant: 0)
        imgCenterY.identifier = "imgCenterY"
        imgCenterY.isActive = true

        let imgRight = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .right,
                           relatedBy: .equal,
                           toItem: totalAmountView,
                           attribute: .right,
                           multiplier: 1.0,
                           constant: 16)
        imgRight.identifier = "imgRight"
        imgRight.isActive = true

        let imgAspectRatio = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .height,
                           relatedBy: .equal,
                           toItem: totalAmountImg,
                           attribute: .width,
                           multiplier: 1.0 / 1.0,
                           constant: 0)
        imgAspectRatio.identifier = "imgAspectRatio"
        imgAspectRatio.isActive = true

        let imgLeft = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .left,
                           relatedBy: .equal,
                           toItem: totalPriceLbl,
                           attribute: .right,
                           multiplier: 1.0,
                           constant: 4)
        imgLeft.identifier = "imgLeft"
        imgLeft.isActive = true

        let imgWidth = NSLayoutConstraint(item: totalAmountImg,
                           attribute: .width,
                           relatedBy: .lessThanOrEqual,
                           toItem: totalAmountView,
                           attribute: .width,
                           multiplier: 0.2,
                           constant: 0)
        imgWidth.identifier = "imgWidth"
        imgWidth.isActive = true
    }



    //-----------------------------------------------------------------
    // MARK: - Actions
    //-----------------------------------------------------------------

    @IBAction func pageChange(_ sender: UIPageControl) {
        let x = CGFloat(sender.currentPage) * scrollView.frame.width
        scrollView.contentOffset = CGPoint(x: x, y: 0)
        pageController.currentPageIndicatorTintColor = UIColor.white
    }

}


extension NSLayoutConstraint {


    override open var description: String {
        let id = identifier ?? ""
        return "id: \(id), constant: \(constant)" //you may print whatever you want here
    }
}

日志

2018-01-12 16:27:27.934408+0530 Cafe Point[13577:258401] [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. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "id: , constant: 343.0",
    "id: , constant: 0.0",
    "id: , constant: 0.0",
    "id: , constant: 16.0",
    "id: , constant: 0.0",
    "id: , constant: 0.0",
    "id: , constant: 0.0",
    "id: imgLeft, constant: 4.0",
    "id: imgRight, constant: 16.0",
    "id: imgWidth, constant: 0.0"
)

Will attempt to recover by breaking constraint 
id: imgLeft, constant: 4.0

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

Answer 1

试着改成这样:

    let imgRight = NSLayoutConstraint(item: totalAmountImg,
                       attribute: .right,
                       relatedBy: .equal,
                       toItem: totalAmountView,
                       attribute: .right,
                       multiplier: 1.0,
                       constant: -16)
    imgRight.identifier = "imgRight"
    imgRight.isActive = true

(注意 16 变为 -16)

比较 Storyboard 中的约束与以编程方式创建的约束时必须小心，因为顺序很重要。