循环多个 UIAlertController 的 [英] Loop over multiple UIAlertController's

问题描述

在某些情况下，我的应用程序需要显示多个警报消息.错误消息是在启动时收集的，需要一次向用户显示一个.当第一个被确认时，应该呈现下一个.问题是，很明显，它们都试图同时执行.有没有一种聪明的方法可以同步执行此操作?下面是一些简单描述我想要做什么的代码:

In some cases my applications needs to display muliple Alert messages. Error messages are gathered on start and needs to be displayed to the user one at a time. When the first one is acknowledged, the next one should be presented. The problem is that they all try to execute at the same time, obviously. Is there a smart way to do this synchronously? Here is some code that simply describes what I want to do:

var errors : [NSError]!

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    let error1 = NSError(domain: "Test1", code: 1, userInfo: [NSLocalizedFailureReasonErrorKey : "Test1 reason."])

    let error2 = NSError(domain: "Test2", code: 2, userInfo: [NSLocalizedFailureReasonErrorKey : "Test2 reason."])

    let error3 = NSError(domain: "Test3", code: 2, userInfo: [NSLocalizedFailureReasonErrorKey : "Test3 reason."])

    errors = [error1, error2, error3]

}

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

    for error in errors {

        self.showAlert(error)

    }

}

func showAlert(error: NSError) {

    var alert = UIAlertController(title: error.domain, message: error.localizedDescription, preferredStyle: .Alert)
    alert.addAction(UIAlertAction(title: "OK", style: .Default, handler:nil))

    self.presentViewController(alert, animated: true, completion: nil)
}

推荐答案

您就快到了.拥有一个警报消息缓冲区是正确的想法.但不是立即显示所有警报，您应该将 showAlert() 调用移动到 UIAlertAction 的处理程序.因此，如果解除了一个警报，则会显示下一个警报.

You are almost there. Having a buffer of alert messages is the correct idea. But instead of showing all the alerts immediately, you should move the showAlert() call to the handler of the UIAlertAction. So if one alert is dismissed, the next will be shown.

像这样:

var errors : [NSError]!

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

    let error1 = NSError(domain: "Test1", code: 1, userInfo: [NSLocalizedFailureReasonErrorKey : "Test1 reason."])
    let error2 = NSError(domain: "Test2", code: 2, userInfo: [NSLocalizedFailureReasonErrorKey : "Test2 reason."])
    let error3 = NSError(domain: "Test3", code: 2, userInfo: [NSLocalizedFailureReasonErrorKey : "Test3 reason."])

    errors = [error1, error2, error3]

    showError() // show an alert if errors are queued
}

func showError() {
    if let error = errors.first {
        let alert = UIAlertController(title: error.domain, message: error.localizedDescription, preferredStyle: .Alert)
        let okayAction = UIAlertAction(title: "OK", style: .Default) { action in
            self.errors.removeAtIndex(0) // remove the message of the alert we have just dismissed

            self.showError() // show next alert if there are more errors queued
        }
        alert.addAction(okayAction)
        presentViewController(alert, animated: true, completion: nil)
    }
    else {
        println("All alerts shown")
    }
}

<小时>

忠告:关闭多个警报非常烦人.也许您可以创建一个专用的全屏 viewController 来显示 UITableView 或其他内容中的所有错误消息.这当然取决于典型用户将看到的警报消息的数量.如果它经常超过三个，我会使用一个模式 UIViewController，它可以一目了然地显示所有消息.

---

Word of advice: Dismissing multiple alerts is very annoying. Maybe you could create a dedicated full screen viewController that shows all the error messages in a UITableView or something. This of course depends on the number of alert messages a typical user will see. If it's regularly more than three I would use a modal UIViewController which shows all messages at a glance.

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