Is there any way to check if iOS app is in background?

问题

I want to check if the app is running in the background.

In:

locationManagerDidUpdateLocation {
    if(app is runing in background){
        do this
    }
}

回答1:

App delegate gets callbacks indicating state transitions. You can track it based on that.

Also the applicationState property in UIApplication returns the current state.

[[UIApplication sharedApplication] applicationState]

回答2:

UIApplicationState state = [[UIApplication sharedApplication] applicationState];
if (state == UIApplicationStateBackground || state == UIApplicationStateInactive)
{
   //Do checking here.
}

This may help you in solving your problem.

See comment below - inactive is a fairly special case, and can mean that the app is in the process of being launched into the foreground. That may or may not mean "background" to you depending on your goal...

回答3:

Swift 3

    let state = UIApplication.shared.applicationState
    if state == .background {
        print("App in Background")
    }

回答4:

Swift version :

   let state = UIApplication.sharedApplication().applicationState
            if state == .Background {
                print("App in Background")
             }

回答5:

If you prefer to receive callbacks instead of "ask" about the application state, use these two methods in your AppDelegate:

- (void)applicationDidBecomeActive:(UIApplication *)application {
    NSLog(@"app is actvie now");
}


- (void)applicationWillResignActive:(UIApplication *)application {
    NSLog(@"app is not actvie now");
}

回答6:

swift 5

let state = UIApplication.shared.applicationState
    if state == .background {
        print("App in Background")
        //MARK: - if you want to perform come action when app in background this will execute 
        //Handel you code here
    }
    else if state == .foreground{
        //MARK: - if you want to perform come action when app in foreground this will execute 
        //Handel you code here
    }

回答7:

Swift 4+

let appstate = UIApplication.shared.applicationState
        switch appstate {
        case .active:
            print("the app is in active state")
        case .background:
            print("the app is in background state")
        case .inactive:
            print("the app is in inactive state")
        default:
            print("the default state")
            break
        }

回答8:

A Swift 4.0 extension to make accessing it a bit easier:

import UIKit

extension UIApplication {
    var isBackground: Bool {
        return UIApplication.shared.applicationState == .background
    }
}

To access from within your app:

let myAppIsInBackground = UIApplication.shared.isBackground

If you are looking for information on the various states (active, inactive and background), you can find the Apple documentation here.

来源：https://stackoverflow.com/questions/5835806/is-there-any-way-to-check-if-ios-app-is-in-background