我定义了一堆这样的自定义错误:
enum FilesystemError: Error {
case cannotMove(String)
case cannotDelete(String)
}
enum MediaError: Error {
case cannotRecordVideo(String)
case cannotLoadPhoto(String)
}
现在,如果引发错误,我将使用此辅助功能将其呈现给用户:
public func presentErrorAlert(presentingViewController: UIViewController, error: Error) {
let title: String
let message: String
if let error = error as? FilesystemError {
switch(error) {
case .cannotMove(let msg):
title = "Failed to move"
message = msg
case .cannotDelete(let msg):
title = "Failed to delete"
message = msg
}
}
else if let error = error as? MediaError {
switch(error) {
case .cannotLoadPhoto(let msg):
title = "Failed to load photo"
message = msg
case .cannotRecordVideo(let msg):
title = "Failed to record video"
message = msg
}
}
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertController.Style.alert)
alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
presentingViewController.present(alert, animated: true, completion: nil)
}
我的代码中有很多错误,并且发生了太多“消息= msg”。感觉必须有一种更简单的方法来执行此操作。有什么想法可以优雅地规避吗?
答案 0 :(得分:0)
让我们定义:
protocol ErrorFormattable: Error {
var errorTitle: String { get }
var errorMessage: String { get }
}
使您的错误类型符合ErrorFormattable。然后在presentErrorAlert中,只需检查:
if let error = error as? ErrorFormattable {
title = error.errorTitle
message = error.errorMessage
}