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swiftuitableviewcore-datauitabbarcontrollernsfetchedresultscontroller

How to correctly update TabBarItem's badge value?

I have a three tableViewController and they’re managed by the tabBarController. And each tabBarItem must be alerted about overdue items like any others apps. In my first tableViewController I’ve tried to show overdue items count inside of the tabBarItem’s badgeValue. These values are comes from the fetchedResultsController’s fetchedObjects.count, it well working condition.

func tabBarBadgeUpdater() {

    for viewController in (self.tabBarController?.viewControllers)! {

        let overdue = self.fetchedResultsController.fetchedObjects?.filter({ (record) -> Bool in
            return (record.date?.compare(Date()) != .orderedDescending)
        })

        print(overdue!.count)

        if viewController.tabBarItem.tag == 1 {

            if overdue!.count != 0 {
                DispatchQueue.main.async(execute: {
                    viewController.tabBarItem.badgeValue = "\(overdue!.count)"
                    viewController.tabBarItem.badgeColor = UIColor.init(red: 0.0, green: 0.5, blue: 0.0, alpha: 1.0)
                    self.tableView.reloadData()
                })
            } else {
                DispatchQueue.main.async(execute: {
                    viewController.tabBarItem.badgeValue = ""
                    viewController.tabBarItem.badgeColor = .clear
                    self.tableView.reloadData()
                })
            }
        }
    }
}

But my problem line is deleting them. When I tried to delete last object from the model and it’s still shows value 1.

Before deleting

After deleted

How to correctly show TabBarItem's badgeValue ?

Solution

  • I recommend that you implement controllerDidChangeContent which is a delegate method of your fetchedResultsController. Everytime your model changes this will be called, and you can query the count and update your badge number.