ios 快速检测应用程序是在后台还是前台

Detect if the application in background or foreground in swift

提问by Mohammed Aboelwafa

is there any way to know the state of my application if it is in background mode or in foreground . Thanks

有没有办法知道我的应用程序的状态，如果它处于后台模式或前台。谢谢

回答by Anbu.Karthik

[UIApplication sharedApplication].applicationStatewill return current state of applications such as:

[UIApplication sharedApplication].applicationState将返回应用程序的当前状态，例如：

• UIApplicationStateActive
• UIApplicationStateInactive
• UIApplicationStateBackground

• UIApplicationStateActive
• UIApplicationStateInactive
• UIApplicationStateBackground

or if you want to access via notification see UIApplicationDidBecomeActiveNotification

或者如果您想通过通知访问，请参阅UIApplicationDidBecomeActiveNotification

Swift 3+

斯威夫特 3+

let state = UIApplication.shared.applicationState
if state == .background || state == .inactive {
    // background
} else if state == .active {
    // foreground
}

switch UIApplication.shared.applicationState {
    case .background, .inactive:
        // background
    case .active:
        // foreground
    default:
        break
}

Objective C

目标 C

UIApplicationState state = [[UIApplication sharedApplication] applicationState];
if (state == UIApplicationStateBackground || state == UIApplicationStateInactive) {
    // background
} else if (state == UIApplicationStateActive) {
    // foreground
}

回答by dimo hamdy

Swift 3

斯威夫特 3

  let state: UIApplicationState = UIApplication.shared.applicationState

            if state == .background {

                // background
            }
            else if state == .active {

                // foreground
            }

回答by Ashu

Swift 4

斯威夫特 4

let state = UIApplication.shared.applicationState
        if state == .background {
            print("App in Background")
        }else if state == .active {
            print("App in Foreground or Active")
        }

回答by Hamid Shahsavari

If somebody wants it in swift 3.0

如果有人想要 swift 3.0

switch application.applicationState {
    case .active:
        //app is currently active, can update badges count here
        break
    case .inactive:
        //app is transitioning from background to foreground (user taps notification), do what you need when user taps here
        break
    case .background:
        //app is in background, if content-available key of your notification is set to 1, poll to your backend to retrieve data and update your interface here
        break
    default:
        break
    }

for swift 4

快速 4

switch UIApplication.shared.applicationState {
case .active:
    //app is currently active, can update badges count here
    break
case .inactive:
    //app is transitioning from background to foreground (user taps notification), do what you need when user taps here
    break
case .background:
    //app is in background, if content-available key of your notification is set to 1, poll to your backend to retrieve data and update your interface here
    break
default:
    break
}

回答by Atlandu

you can add a boolean when the application enter in background or enter in foreground. You have this information by using the App delegate.

当应用程序进入后台或进入前台时，您可以添加一个布尔值。您可以使用 App 委托获得此信息。

According the Apple documentation, maybe you can also use the mainWindow property of your Application or the active status property of the app.

根据 Apple 文档，也许您还可以使用应用程序的 mainWindow 属性或应用程序的活动状态属性。

NSApplication documentation

NS应用文档

Discussion The value in this property is nil when the app's storyboard or nib file has not yet finished loading. It might also be nil when the app is inactive or hidden.

讨论 当应用程序的故事板或 nib 文件尚未完成加载时，此属性中的值为 nil。当应用程序处于非活动状态或隐藏状态时，它也可能为零。