我有一个主课,AddFriendsController
,运行以下代码行:
ErrorReporting.showMessage("Error", msg: "Could not add student to storage.")
然后我有这个ErrorReporting.swift
file:
进口基金会
class ErrorReporting {
func showMessage(title: String, msg: String) {
let alert = UIAlertController(title: title, message: msg, preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil))
self.presentViewController(alert, animated: true, completion: nil)
}
}
明显地,self
在这里不起作用,并且给我一个错误。我如何引用当前打开的视图控制器(即AddFriendsController
在这种情况下),因为我希望在许多不同的 swift 文件中使用相同的方法?
Thanks.
您可以为 UIApplication 创建扩展方法(例如),它将返回您的 topViewController:
extension UIApplication {
static func topViewController(base: UIViewController? = UIApplication.sharedApplication().delegate?.window??.rootViewController) -> UIViewController? {
if let nav = base as? UINavigationController {
return topViewController(nav.visibleViewController)
}
if let tab = base as? UITabBarController, selected = tab.selectedViewController {
return topViewController(selected)
}
if let presented = base?.presentedViewController {
return topViewController(presented)
}
return base
}
}
然后你的类将如下所示:
class ErrorReporting {
static func showMessage(title: String, msg: String) {
let alert = UIAlertController(title: title, message: msg, preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil))
UIApplication.topViewController()?.presentViewController(alert, animated: true, completion: nil)
}
}
方法需要是static
能够将其称为ErrorReporting.showMessage
.
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