CODEWITHSUNDEEP
iosxcodeswiftswift2
Nick Pitoniak
Nick Pitoniak

Reputation: 97

Code that otherwise runs well is crashing application when used in viewDidLoad()

I am working on an application that retrieves a user's friends from a database and outputs then in a table view.

I have successfully coded the table view to the point where it reads the indexes I insert into an NSMutableArray(). My thinking is to use NSURL to send a query to a MySQL database via URL variables with PHP.

I have used NSURL many times to interact with the database, however when I use it in the viewDidLoad() function to load the friends immediately on the application's load, it crashes but does not return an error.

Code:

class viewFriendsViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    @IBOutlet weak var tableView: UITableView!

    var textArray: NSMutableArray = NSMutableArray()

    override func viewDidLoad() {
        super.viewDidLoad()

        let myUrl = NSURL(string: "http://www.casacorazon.org/ios.html")
        let request = NSMutableURLRequest(URL: myUrl!)
        request.HTTPMethod = "POST"
        let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
            data, response, error in
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)) {
                let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
                if error != nil {
                    print("Error: \(error)")
                }
                dispatch_async(dispatch_get_main_queue()) {
                    print(responseString)
                }
            }
        }
        task.resume()
        //get username from NSUserDefaults
            //if username inavailable, insert error report into first row
        //use PHP script to get friends from user's database
        //split return string by '9245203598' into array
        //load split array into NSMutableArray via foreach loop
        //let username = NSUserDefaults.standardUserDefaults().stringForKey("username")*/
        self.textArray.addObject("First Index")
        self.textArray.addObject("Second Index")
        self.textArray.addObject("Third Index")
        self.tableView.rowHeight = UITableViewAutomaticDimension
        self.tableView.estimatedRowHeight = 44.0
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()

    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.textArray.count
    }

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        var cell: UITableViewCell = self.tableView.dequeueReusableCellWithIdentifier("cell")! as UITableViewCell
        cell.textLabel?.text = self.textArray.objectAtIndex(indexPath.row) as? String
        return cell
    }

    func sendAlert(subject: String, message: String) {
        let alertController = UIAlertController(title: subject, message:
            message, preferredStyle: UIAlertControllerStyle.Alert)
        alertController.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.Default,handler: nil))

        self.presentViewController(alertController, animated: true, completion: nil)
    }
}

Upvotes: 1

Views: 80

Answers (1)

Hussein Alzand
Hussein Alzand

Reputation: 169

because your app complete excuting the code in UI before the background finish its task. you have to ensure that background task is completed then continue in UI.

Note: NSUrlsesstion is running in background you don't have to import dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)) {} inside it.

Upvotes: 2

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