我如何知道是否以编程方式迅速更改了标签栏控制器索引？

Question

So I am writing a little something in swift that uses a tab bar controller with four tabs, each are fully functioning on their own. However in the main tab I select the best value from an array and provide a link to it. The array is presented in the second tab.

I have a code like this:

override func viewWillAppear(animated: Bool) {
        // some other stuff

        if dataManager.ideas.count > 0 {
            lblAllTimeBest.text = "Our all time best with a rating of \(dataManager.ideas[dataManager.allTimeBest].averageRating)% is:"

            btnAllTimeBest.hidden = false
             btnAllTimeBest.setTitle(dataManager.ideas[dataManager.allTimeBest].title, forState: UIControlState.Normal)

        //and some more stuff
    }

    @IBAction func btnAllTimeBestTapped(sender: AnyObject) {
            tabBarController?.selectedIndex = 1
    }

I present the items of the array on the second tab based on array index. How do I pass the index (I store it in datamanager already) to the second tab OR how do I know on the second tab that it was presented using the button on the first one?

Answer 1

You can try these options (in order of "recommendedness"):

1. keep a reference to the second controller (or retrieve it ad hoc from the tab bar controller) and implement a message in the second controller that the first controller can call explicitly
2. send an NSNotification via NSNotificationCenter and listen to it in the second controller
3. (not recommended) use some kind of global variable that the second controller can check