ios - Swift Playground 错误 : Execution was interrupted, 原因:信号 SIGABRT

Question

如何调试这个错误？似乎没有额外的错误描述。

失败的代码:

import UIKit
import PlaygroundSupport

let containerView = UIView(frame: CGRect(x: 0, y: 0, width: 300, height: 300))
containerView.backgroundColor = UIColor.white

let stackView = UIStackView()
stackView.translatesAutoresizingMaskIntoConstraints = false
containerView.addSubview(stackView)
stackView.addConstraint(.init(item: stackView, attribute: .top, relatedBy: .equal, toItem: containerView, attribute: .top, multiplier: 1, constant: 0))
stackView.addConstraint(.init(item: stackView, attribute: .leading, relatedBy: .equal, toItem: containerView, attribute: .leading, multiplier: 1, constant: 0))

PlaygroundPage.current.liveView = containerView // error: Execution was interrupted, reason: signal SIGABRT.

完整错误:

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.

完整控制台日志:

libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

问题是您将约束添加到 stackView 而不是 containerView。

documentation for addConstraint州

The constraint to be added to the view. The constraint may only reference the view itself or its subviews.

containerView是stackView的 super View ，而不是 subview 。

如果您更改代码以将约束添加到 containerView 它将运行

containerView.addConstraint(.init(item: stackView, attribute: .top, relatedBy: .equal, toItem: containerView, attribute: .top, multiplier: 1, constant: 0))
containerView.addConstraint(.init(item: stackView, attribute: .leading, relatedBy: .equal, toItem: containerView, attribute: .leading, multiplier: 1, constant: 0))

您可能需要添加尾随和底部约束，以便堆栈 View 填充整个容器 View 。当然，您还需要添加一个 arrangedSubview 以便堆栈 View 中实际上有一些内容。

通过引用布局指南来添加约束通常比这种旧的、更冗长的方法更简单:

import UIKit
import PlaygroundSupport

let containerView = UIView(frame: CGRect(x: 0, y: 0, width: 300, height: 300))
containerView.backgroundColor = UIColor.white

let stackView = UIStackView()
stackView.translatesAutoresizingMaskIntoConstraints = false
containerView.addSubview(stackView)

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


let label = UILabel()
label.text = "Hello world"
label.textColor = .black
stackView.addArrangedSubview(label)
PlaygroundPage.current.liveView = containerView