App content, such as an app notification, is displayed on a lock screen or home screen of a mobile device even when the app is closed. In contrast to present app content, the content may be full-screen, engaging, interactive, and media-rich. An app content SDK is inserted into an app and works directly with native app software. The content SDK determines whether the app has permission to display content on, for example, a lock screen. It may also determine whether the app has priority in displaying the content. The content itself is retrieved either from a content server or from the app itself. In either case, the retrieval and display of the content is coordinated and managed by the SDK which may use other constraints, such as date / time, geographic location, and device motion patterns to determine which content should be displayed.