Question

在iOS 12.2上。在使用UIAlertController的actionSheet Xcode时，遇到此问题的人都会遇到约束错误

相同的代码可以在iOS 12.1上运行且没有错误

我已经在Xcode 10.2和10.1上测试了此代码

class ViewController: UIViewController {

    let Click : UIButton = {
        let button = UIButton(type: UIButton.ButtonType.system)
        button.translatesAutoresizingMaskIntoConstraints = false
        button.setTitle("OK", for: .normal)
        button.tintColor = UIColor.blue
        button.addTarget(self, action: #selector(click(_:)), for: UIControl.Event.touchUpInside)
        return button
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
        view.addSubview(Click)
        Click.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        Click.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
    }


    @objc func click(_ sender: UIButton) {
        let optionMenu = UIAlertController(title: nil, message: "Choose Option", preferredStyle: .actionSheet)

        let deleteAction = UIAlertAction(title: "Delete", style: .default)
        let saveAction = UIAlertAction(title: "Save", style: .default)

        let cancelAction = UIAlertAction(title: "Cancel", style: .cancel)

        optionMenu.addAction(deleteAction)
        optionMenu.addAction(saveAction)
        optionMenu.addAction(cancelAction)

        self.present(optionMenu, animated: true, completion: nil)
    }

}

[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. 
(
    "<NSLayoutConstraint:0x6000001b6ee0 UIView:0x7fe3b6513020.width == - 16   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x6000001b6ee0 UIView:0x7fe3b6513020.width == - 16   (active)>

PS：

只是为了确保问题在UIAlertController上，我删除了所有内容并更新了如下代码，但存在相同的错误。

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        let optionMenu = UIAlertController(title: "Test", message: "Choose Option", preferredStyle: .actionSheet)

        let deleteAction = UIAlertAction(title: "Delete", style: .default)
        let saveAction = UIAlertAction(title: "Save", style: .default)

        let cancelAction = UIAlertAction(title: "Cancel", style: .cancel)

        optionMenu.addAction(deleteAction)
        optionMenu.addAction(saveAction)
        optionMenu.addAction(cancelAction)

        self.present(optionMenu, animated: true, completion: nil)
    }

}

Answer 1

这是iOS版本中的新错误：

12.2
12.3
13 beta 2

我们唯一能做的就是向Apple提交错误报告（确实如此）。

我将尝试发布新版本的iOS的答案。

UIAlertController的actionSheet在iOS 12.2 / 12.3上给出了约束错误

1 个答案: