搜索和过滤数组Firebase数据swift3

Question

My app crashing while search a text in a searchbar with error: thread1:signal SIGABRT probably the problem updateSearchResults() method? or type of array? I'm beginner with swift any idea?

@IBOutlet weak var tableView: UITableView!

var data = [Any]()
var ref:FIRDatabaseReference!

// Filter Data from Firebase
var filteredData = [Any]()

// Declare searchBar

let searchController = UISearchController(searchResultsController: nil)


//is the device landscape or portrait
var isPortraid = true

@IBOutlet weak var bannerView: GADBannerView!



func fetchDataFromFirebase(){
    EZLoadingActivity.show("caricamento...", disableUI: true)
    ref = FIRDatabase.database().reference()
    ref.observe(.value, with: { (snapshot) in
        let dataDict = snapshot.value as! NSDictionary
        self.data = dataDict["data"] as! [Any]
        self.filteredData = self.data
        print ("Sacco di merda:\(self.filteredData)")
        self.tableView.reloadData()
        EZLoadingActivity.hide()
    })
}



override func viewDidLoad() {
    super.viewDidLoad()


    tableView.delegate = self
    fetchDataFromFirebase()

    //  Implement searchBar
    searchController.searchResultsUpdater = self
    searchController.dimsBackgroundDuringPresentation = false
    definesPresentationContext = true
    tableView.tableHeaderView = searchController.searchBar




    NotificationCenter.default.addObserver(self, selector: #selector(MainViewController.orientationChanged), name: NSNotification.Name.UIDeviceOrientationDidChange, object: nil)


}


//TableView Data Source and Delegate


func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}


func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

    return filteredData.count
}


func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell = tableView.dequeueReusableCell(withIdentifier: "MainCell", for:indexPath) as! MainScreenTableViewCell
    let rowData = self.filteredData[indexPath.row] as! NSDictionary
    let imageName  = rowData["imageName"] as! String
    cell.backgroundImageView.image = UIImage(named: imageName)

    let label = rowData["categoryName"] as! String
    cell.mealCategoryLabel.text = label
    return cell
}



func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

    let storyboard = UIStoryboard(name: "Main", bundle: Bundle.main)
    let categoryViewController = storyboard.instantiateViewController(withIdentifier: "CategoryViewController") as! CategoryViewController
    let rowData = self.data[indexPath.row] as! NSDictionary
    categoryViewController.categoryTitle = rowData["categoryName"] as! String
    let categoryData = rowData["category"] as! [Any]
    categoryViewController.data = categoryData
    self.navigationController?.pushViewController(categoryViewController, animated: true)

}





func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    if isPortraid {
    return UIScreen.main.bounds.height/3
    } else {
        return UIScreen.main.bounds.height/1.2
    }
}

//Method for update search

func updateSearchResults(for searchController: UISearchController) {
    if searchController.searchBar.text! == ""{
        filteredData = data
    } else {
        filteredData = data.filter{($0 as AnyObject).contains(searchController.searchBar.text!)}

    }
    self.tableView.reloadData()
}

Answer 1

if searchController.searchBar.text! == ""

This is almost certainly the offender. The text property on UI objects is typically nil when it's empty, so when you force unwrap it your app crashes. You should never force unwrap something unless you are absolutely certain it will never be nil at that point.

There's a couple different ways you can handle this, which basically amount to making sure text isn't nil before you do anything with it.

Personally I would rewrite the if statement to unwrap the optional for the non-empty case:

if let text = searchController.searchBar.text, text != "" {
    filteredData = data.filter{($0 as AnyObject).contains(text)}
} else {
    filteredData = data
}

You could also use nil-coalescing :

if (searchController.searchBar.text ?? "") == ""

but personally I prefer to write it to avoid force unwrapping even when you're sure it isn't nil, so I would recommend the first one.