scheduleBackgroundRefresh(withPreferredDate:userInfo:scheduledCompletion:)
Schedules a background task to refresh the app’s data.
Declaration
func scheduleBackgroundRefresh(withPreferredDate preferredFireDate: Date, userInfo: (any NSSecureCoding & NSObjectProtocol)?, scheduledCompletion: @escaping ((any Error)?) -> Void)Parameters
- preferredFireDate:
The date and time of the next background app refresh task. The system attempts to wake your app in the background shortly after the scheduled time, but may delay the background task due to the system’s current state or if your app exceeds its budget for background tasks.
- userInfo:
A dictionary of custom information associated with the background app refresh task. Pass
nilif you don’t need to associate any custom data with the task. - scheduledCompletion:
A block that the system calls after scheduling the background app refresh task. This block takes the following parameter:
- error
If an error occurs, this parameter contains an object describing the error; otherwise, it’s
nil.
Mentioned in
Discussion
Call this method to update the contents of your app in the background. Background refresh tasks only trigger when the app is in the background. If the app is still running in the foreground at the scheduled time, the system ignores the task.
When the system triggers the task, it wakes your app in the background and execute your background task handler. The system also calls your active interface controller’s willActivate() and didActivate() methods. You can check your app’s applicationState during these methods to determine whether your app is running in the foreground or in the background.
Use this task to update your application’s state. You can only schedule one background app refresh task at a time; scheduling a second task cancels the first. Additionally, the system budgets background app refresh tasks. For more information, see WKApplicationRefreshBackgroundTask.