在某些情况下,我的应用程序需要显示多个警报消息。错误消息是在开始时收集的,需要一次向用户显示。当第一个被确认时,应显示下一个。问题在于,它们显然都试图同时执行。是否有同步执行此操作的明智方法?这是一些简单地描述我要做什么的代码:
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)
}
你快到了。拥有警报消息缓冲区是正确的想法。但是,您应该将showAlert()
调用移至的处理程序,而不是立即显示所有警报UIAlertAction
。因此,如果关闭了一个警报,则将显示下一个警报。
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")
}
}
忠告:消除多个警报非常烦人。也许您可以创建一个专用的全屏viewController,以在UITableView或其他内容中显示所有错误消息。当然,这取决于典型用户将看到的警报消息的数量。如果通常超过三个,我将使用模式UIViewController,一目了然地显示所有消息。
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