错误：执行被中断，原因：信号 SIGABRT。在快速的操场上

Question

当我尝试在 Xcode 中运行 Playground 时出现此错误：

error: Execution was interrupted, reason: signal SIGABRT.
The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.

这是我的游乐场代码：

import UIKit
import PlaygroundSupport

class MyViewController : UIViewController {
    override func loadView() {
        let view = UIView()
        view.backgroundColor = .white

        let titleLabel = UILabel()
        titleLabel.frame = CGRect(x: 150, y: 200, width: 200, height: 20)
        titleLabel.text = "Title"
        titleLabel.textColor = .black

        let subtitleLabel = UILabel()
        subtitleLabel.text = "Subtitle"
        subtitleLabel.textColor = .gray
        subtitleLabel.frame = CGRect(x: 150, y: 200, width: 200, height: 20)

        NSLayoutConstraint.activate([
            titleLabel.bottomAnchor.constraint(equalToSystemSpacingBelow: subtitleLabel.topAnchor, multiplier: 10)
        ])

        view.addSubview(subtitleLabel)
        view.addSubview(titleLabel)
        self.view = view
    }
}
PlaygroundPage.current.liveView = MyViewController()

如何解决此错误？这是 Xcode 中的错误吗？还是我的代码有问题？

Answer 1

在 loadView 方法中重新排序代码。在添加约束之前向上移动 addSubview

view.addSubview(subtitleLabel)
view.addSubview(titleLabel)

NSLayoutConstraint.activate([
            titleLabel.bottomAnchor.constraint(equalToSystemSpacingBelow: subtitleLabel.topAnchor, multiplier: 10)
        ])

self.view = view

错误会消失。