ios - @IBDesignables - "the agent crashed"但应用程序仍然有效(大部分时间)

Question

我在一个项目中遇到了一个非常奇怪的问题。 XCode 一直给我红色错误，并说我的 IBDesignables 有问题。但是错误消息每次都不同，而且总是受到影响的另一个 View Controller 。我不知道如何找到问题的原因。我创建的所有 IBDesignables 似乎都是随机发生的。

该应用程序仍然有效。虽然，有时它无法正确呈现某些 View (我有带有自定义绘制 mask 的 View )。它很少发生，但确实发生了。

这些是我得到的错误:

"Failed to update the auto layout status: The agent crashed"

"Failed to render and update the auto layout status for {randomly chosen VC name}: The agent crashed"

后者在我点击后立即消失。有时，当我进入 Storyboard时，所有的错误都会消失。当我打开任何其他文件时，我会收到多个红色错误(有时是 3 个，有时是 6 个或更多)。

我检查了崩溃日志。他们每个人都说:

fatal error: unexpectedly found nil while unwrapping an Optional value

我不确定这是什么意思。

我尝试清理项目并重新启动 XCode。此外，我还实现了所有 init 方法。

下面的代码是一个类，它(几乎)总是我得到的错误的一部分。此外，自定义绘制的 View 有时无法正确呈现:

import UIKit

struct TriangleViewLabelDefault {
    static let triangleWidth: CGFloat = 20
    static let triangleHeight: CGFloat = 10
}

@IBDesignable
class TriangleView: UIView {
    let DEFAULT_TRIANGLE_WIDTH: CGFloat = 30
    let DEFAULT_TRIAGNLE_HEIGHT: CGFloat = 20


    struct Triangle {
        static var width: CGFloat = TriangleViewLabelDefault.triangleWidth
        static var height: CGFloat = TriangleViewLabelDefault.triangleHeight
        static var midXPosition: CGFloat = 0
    }

    @IBInspectable var triangleWidth: CGFloat = TriangleViewLabelDefault.triangleWidth {
        didSet {
            Triangle.width = triangleWidth
        }
    }

    @IBInspectable var triangleHeight: CGFloat = TriangleViewLabelDefault.triangleHeight {
        didSet {
            Triangle.height = triangleHeight
        }
    }

    @IBInspectable var relativePosition: Bool = true {
        didSet {
            setNeedsDisplay()
        }
    }

    @IBInspectable var triangleMidXOffset: CGFloat = 0 {
        didSet {
            setNeedsDisplay()
        }
    }

    @IBInspectable var decoration: Bool = true {
        didSet {
            setNeedsDisplay()
        }
    }

    @IBInspectable var lines: Int = 20 {
        didSet {
            setNeedsDisplay()
        }
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    override func draw(_ rect: CGRect) {
        super.draw(rect)
        calcTriangleMidXPosition()
        addLines()
        if decoration {
            addDecoration()
        }

        let maskLayer = CAShapeLayer()
        maskLayer.frame = bounds

        let maskPath = UIBezierPath()
        maskPath.move(to: CGPoint(x: 0, y: Triangle.height))
        /* Triangle */
        maskPath.addLine(to: CGPoint(x: Triangle.midXPosition - Triangle.width, y: Triangle.height))
        maskPath.addLine(to: CGPoint(x: Triangle.midXPosition, y: 0))
        maskPath.addLine(to: CGPoint(x: Triangle.midXPosition + Triangle.width, y: Triangle.height))
        /* */
        maskPath.addLine(to: CGPoint(x: bounds.size.width, y: Triangle.height))
        maskPath.addLine(to: CGPoint(x: bounds.size.width, y: bounds.size.height))
        maskPath.addLine(to: CGPoint(x: 0, y: bounds.size.height))
        maskPath.addLine(to: CGPoint(x: 0, y: Triangle.height))

        maskPath.close()

        maskLayer.path = maskPath.cgPath
        layer.mask = maskLayer
    }

    /// Evaluates the properties set in storyboard. This methods calculates the x-center of the triangle
    private func calcTriangleMidXPosition() {
        if relativePosition {
            Triangle.midXPosition = bounds.size.width / 2 + triangleMidXOffset * bounds.size.width / 2
        } else {
            Triangle.midXPosition = bounds.size.width / 2 + triangleMidXOffset
        }
    }

    private func addDecoration() {
        if let superview = superview {

            let topLine = UIView(frame: CGRect(x: 0, y: frame.minY + Triangle.height - 2, width: bounds.size.width, height: 1))
            let bottomLine = UIView(frame: CGRect(x: 0, y: frame.minY + Triangle.height - 4, width: bounds.size.width, height: 1))

            topLine.backgroundColor = UIColor.white
            bottomLine.backgroundColor = UIColor.white

            topLine.alpha = 0.5
            bottomLine.alpha = 0.2

            superview.insertSubview(topLine, belowSubview: self)
            superview.insertSubview(bottomLine, belowSubview: self)
        }
    }

    private func addLines() {

        guard lines > 0 else {
            return
        }

        let paddingLeft: Int = 20
        let lineLength: Int = 25

        let linesLayer = CAShapeLayer()
        linesLayer.frame = bounds

        let padding: CGFloat = 20

        let minY = Triangle.height + padding
        let maxY = bounds.height - padding
        let yArea = maxY - minY



        for x in 0...lines {
            let path = UIBezierPath()
            path.lineWidth = 3.0

            path.move(to: CGPoint(x: CGFloat(paddingLeft), y: minY + CGFloat(x) * yArea / CGFloat(lines)))
            path.addLine(to: CGPoint(x: CGFloat(paddingLeft) + CGFloat(lineLength), y: minY + CGFloat(x) * yArea / CGFloat(lines)))

            UIColor(red: 200.0/255.0, green: 200.0/255.0, blue: 200.0/255.0, alpha: 1.0).setStroke()
            path.stroke()
        }
    }
}

谢谢大家的帮助!

Answer 1

每次出现此“代理崩溃”问题时，都会创建一个崩溃日志。您可以在这里找到所有这些:

~/Library/Logs/DiagnosticReports

命名为 IBDesignablesAgentCocoaTouch_*.crash

只需进入 Finder(转到 -> 转到文件夹)，复制路径并替换为您的用户名。

可能你那里有太多崩溃日志，你可以将它们全部删除，清理你的项目，重新构建并检查文件夹。