昨天我升级到Xcode 10.2并开始使用Swift 5,在调用UIAlertController
照片提示时发现了这个错误。我记得在Xcode 10.1中没有看到过它。
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x600001321e00 UIView:0x7fe1246070a0.width == - 16 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
我阅读了这个问题如何在UIViewAlertForUnsatisfiableConstraints上设置陷阱?并且能够将错误定位到我的UIAlertController
(用红色突出显示)
这是我的代码:
@objc private func promptPhoto() {
let prompt = UIAlertController(title: "Choose a Photo",
message: "",
preferredStyle: .actionSheet)
let imagePicker = UIImagePickerController()
imagePicker.delegate = self
let camerAction = UIAlertAction(title: "Camera", style: .default) { _ in
guard self.isCameraAccessible() else {
self.showAlert(title: "Oops", message: "Camera is not available")
return
}
imagePicker.sourceType = .camera
imagePicker.allowsEditing = true
self.present(imagePicker, animated: true)
}
let libraryAction = UIAlertAction(title: "Photo Library", style: .default) { _ in
imagePicker.sourceType = .photoLibrary
imagePicker.allowsEditing = true
self.present(imagePicker, animated: true)
}
let cancelAction = UIAlertAction(title: "Cancel",
style: .cancel,
handler: nil)
prompt.addAction(camerAction)
prompt.addAction(libraryAction)
prompt.addAction(cancelAction)
present(prompt, animated: true) {
// Prevent closing the prompt by touch up outside the prompt.
prompt.view.superview?.subviews[0].isUserInteractionEnabled = false
}
}
我已经尝试过在我的promptPhoto()
方法中使用以下代码设置UIAlertController
的宽度,但没有成功。
let width: NSLayoutConstraint = NSLayoutConstraint(item: prompt.view!,
attribute: NSLayoutConstraint.Attribute.width,
relatedBy: NSLayoutConstraint.Relation.equal,
toItem: nil,
attribute: NSLayoutConstraint.Attribute.notAnAttribute,
multiplier: 1,
constant: self.view.frame.width)
prompt.view.addConstraint(width)
有没有一种方法可以控制
UIAlertController
的宽度,以便我可以摆脱错误消息?谢谢。
Build Setting -> Swift Compiler - Language
中使用Swift 5
还是Swift 4.2
? - Nizzam