如何从UIAlertView迁移（在iOS8中弃用）

问题描述

我目前在其中一个应用中有以下代码行。这是一个简单的 UIAlertView 。但是，从iOS 8开始，现在已弃用：

I currently have the following line of code in one of my apps. It is a simple UIAlertView. However, as of iOS 8, this is now deprecated:

let alertView = UIAlertView(title: "Oops!", message: "This feature isn't available right now", delegate: self, cancelButtonTitle: "OK")

如何更新此设置以使用iOS 8+？我相信我必须改变一些东西到 UIAlertCotroller ，虽然我不太清楚是什么。

How do I update this to work with iOS 8+? I believe I have to change something to UIAlertCotroller, though I'm not too sure what.

推荐答案

您需要使用 UIAlertController 。 非常简单，甚至包含一个用法示例在清单1中的文档的开头（确定它在ObjC中，而不是在Swift中，但它非常相似）。

You need to use UIAlertController instead. To class documentation is pretty straightforward, even containing an usage example in Listing 1 at the very beginning of the doc (sure it's in ObjC and not in Swift but it's quite similar).

所以对于你的用例，这是怎么回事转换为（添加注释）：

So for your use case, here is how it translates to (with added comments):

let alert = UIAlertController(title: "Oops!", message:"This feature isn't available right now", preferredStyle: .alert)
let action = UIAlertAction(title: "OK", style: .default) { _ in
  // Put here any code that you would like to execute when
  // the user taps that OK button (may be empty in your case if that's just
  // an informative alert)
}
alert.addAction(action)
self.presentViewController(alert, animated: true){}

因此紧凑的代码看起来喜欢：

So the compact code will look like:

let alert = UIAlertController(title: "Oops!", message:"This feature isn't available right now", preferredStyle: .Alert)
alert.addAction(UIAlertAction(title: "OK", style: .Default) { _ in })
self.present(alert, animated: true){}

其中 self 这里应该是你的 UIViewController 。

其他提示：如果你需要调用那个在 UIViewController 的上下文之外显示警报的代码，（其中 self 不是 UIViewController ）您可以随时使用应用的根VC：

Additional tip: if you need to call that code that displays the alert outside of the context of an UIViewController, (where self is not an UIViewController) you can always use the root VC of your app:

let rootVC = UIApplication.sharedApplication().keyWindow?.rootViewController
rootVC?.presentViewController(alert, animated: true){}

（但一般情况下，最好使用已知的 UIViewController 当你有一个 - 并且你通常会提出来自UIViewControllers的警报 - 或尝试根据您的背景获得最合适的一个，而不是依赖于此提示）

(But in general it's preferable to use a known UIViewController when you have one — and you generally present alerts from UIViewControllers anyway — or try to get the most suitable one depending on your context instead of relying on this tip)

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