我目前正在开发一款iOS应用，并希望向通知中心添加通知，当且仅当用户在离开应用时正在查看某个视图控制器时。该应用程序有一个倒计时器，如果他们正在查看倒计时器，然后去发送文本或任何其他应用程序，我想在计时器为0时发送通知。但如果他们在另一个视图控制器上我无需发送通知。任何帮助都会非常感谢。
答案 0 :(得分：0)
在您要检测应用程序转到后台的 public static PlotModel ExampleScatterSeriesPlot()
{
var plotModel1 = new PlotModel();
plotModel1.Subtitle = "The scatter points are added to the Points collection.";
plotModel1.Title = "ScatterSeries";
var linearAxis1 = new LinearAxis();
linearAxis1.Position = AxisPosition.Bottom;
plotModel1.Axes.Add(linearAxis1);
var linearAxis2 = new LinearAxis();
plotModel1.Axes.Add(linearAxis2);
var scatterSeries1 = new ScatterSeries();
scatterSeries1.Points.Add(new ScatterPoint(0.667469348137951, 0.701595088793707));
scatterSeries1.Points.Add(new ScatterPoint(7.74765135149828, 5.11139268759237));
scatterSeries1.Points.Add(new ScatterPoint(7.97490558492714, 8.27308291023275));
scatterSeries1.Points.Add(new ScatterPoint(1.65958795308116, 7.36130623489679));
scatterSeries1.Points.Add(new ScatterPoint(2.6021636475819, 5.06004851081411));
scatterSeries1.Points.Add(new ScatterPoint(2.30273722312541, 3.87140443263175));
scatterSeries1.Points.Add(new ScatterPoint(2.15980615101746, 0.208108848989061));
scatterSeries1.ActualPoints.Add(new ScatterPoint(0.667469348137951, 0.701595088793707));
scatterSeries1.ActualPoints.Add(new ScatterPoint(7.74765135149828, 5.11139268759237));
scatterSeries1.ActualPoints.Add(new ScatterPoint(7.97490558492714, 8.27308291023275));
scatterSeries1.ActualPoints.Add(new ScatterPoint(1.65958795308116, 7.36130623489679));
scatterSeries1.ActualPoints.Add(new ScatterPoint(2.6021636475819, 5.06004851081411));
scatterSeries1.ActualPoints.Add(new ScatterPoint(2.30273722312541, 3.87140443263175));
scatterSeries1.ActualPoints.Add(new ScatterPoint(2.15980615101746, 0.208108848989061));
plotModel1.Series.Add(scatterSeries1);
return plotModel1;
}
内，您需要在{UIViewController时注册UIApplicationWillResignActiveNotification和UIApplicationWillTerminateNotification通知NSNotificationCenter 1}}被称为。
viewWillAppear当此屏幕回调您处理通知的方法时，请安排NSNotificationCenter .defaultCenter() .addObserver(self, selector: Selector("callBack"), name: UIApplicationWillResignActiveNotification, object: nil)
NSNotificationCenter .defaultCenter() .addObserver(self, selector: Selector("callBack"), name: UIApplicationWillTerminateNotification, object: nil)
在当前时间触发，再加上计时器计数。您可以UILocalNotification使用init(timeIntervalSinceNow:)进行此操作。
NSDate然后以观察者身份删除var fireDate = NSDate(timeIntervalSinceNow: 25)
var localNotification = UILocalNotification()
localNotification.fireDate = fireDate
UIApplication .sharedApplication() .scheduleLocalNotification(localNotification)
。
UIViewController