快速检测应用程序是在后台还是前台

有什么方法可以知道我的应用程序处于后台模式还是前台模式的状态。谢谢

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

• UI应用程序状态活动
• UIApplicationState非活动状态
• UI应用程序状态背景

或者如果您想通过通知访问，请参阅UIApplicationDidBecomeActiveNotification https://stackoverflow.com/questions/3639859/handling-applicationdidbecomeactive-how-can-a-view-controller-respond-to-the

Swift 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
}

目标C

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