Check For Empty Array From JSON - ios

Question

I am trying to get an array of strings from JSON and I'm trying to figure out how to deal with it if the returned array is empty. In some cases, the returned value is [] and for other cases, the array contains string values. It is crashing because of unexpectedly finding a nil value.
For clarification, the gyms array is passed from another class and everything here works without the code for the images.
Here is my relevant code:
var gyms = [AnyObject]()
var imageArrays = [[String]?]()
In viewDidLoad()
getGymImages()
Methods to get JSON data:
func getGymImages() {
var index = 0
for dictionary in gyms {
let id = dictionary["id"] as! String
let urlString = String("https://gyminyapp.azurewebsites.net/api/GymImage/\(id)")
let url = NSURL(string: urlString)
let data = NSData(contentsOfURL: url!)
do {
let json = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers)
for imageArray in json as! [AnyObject] {
imageArrays.append((imageArray as? [String])!)
}
} catch {
print("Error")
}
index += 1
}
addImagesToGyms()
}
func addImagesToGyms() {
var index = 0;
for array in imageArrays {
var dictionary = gyms[index] as! [String:AnyObject]
dictionary["images"] = array
gyms[index] = dictionary
index += 1
}
}
In cellForRowAtIndexPath()
let gymImages = dictionary["images"] as! [String]
if gymImages.count > 0 {
let firstImageURL = gymImages[0] as String
cell.cellImageView.sd_setImageWithURL(NSURL(string: firstImageURL))
}
EDIT: I was asked to show more of the file, so here it is.
import UIKit
class GymListTableViewController: UITableViewController {
var gyms = [AnyObject]()
var gymName: String?
var gymAddress: String?
var gymPhoneNumber: String?
var gymWebsite: String?
var gymID: String?
var gymLatitude: String?
var gymLongitude: String?
var maxDistance: Double?
var myLocation: CLLocation?
var milesArray = [Double]()
var imageArrays = [[String]?]()
var segmentedControl: UISegmentedControl?
override func viewDidLoad() {
super.viewDidLoad()
self.title = "Gyms"
tableView.registerNib(UINib(nibName: "GymListTableViewCell", bundle: nil), forCellReuseIdentifier: "gymCell")
self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: UIImage(named: "waypoint_map"), style: .Done, target: self, action: #selector(showMapView))
self.navigationItem.rightBarButtonItem?.tintColor = BarItems.greenTintColor
segmentedControl = UISegmentedControl(items: ["A-Z", "Z-A", "Rating", "Distance"])
segmentedControl?.sizeToFit()
segmentedControl?.selectedSegmentIndex = 0
segmentedControl!.setTitleTextAttributes([NSFontAttributeName: UIFont(name:"Helvetica-Light", size: 15)!],
forState: UIControlState.Normal)
segmentedControl?.addTarget(self, action: #selector(changeSelectedSegmentIndex), forControlEvents: .ValueChanged)
self.navigationItem.titleView = segmentedControl
sortAlphabetically()
let backgroundImage = UIImage(named: "gray_background")
let backgroundImageView = UIImageView(image: backgroundImage)
tableView.backgroundView = backgroundImageView
addDistancesToGyms()
getGymImages()
// geocodeAddresses()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func addDistancesToGyms() {
var index = 0
for distance in milesArray {
var dictionary = gyms[index] as! [String:AnyObject]
dictionary["distance"] = distance
gyms[index] = dictionary
index += 1
}
}
func getGymImages() {
var index = 0
for dictionary in gyms {
let id = dictionary["id"] as! String
let urlString = String("https://gyminyapp.azurewebsites.net/api/GymImage/\(id)")
let url = NSURL(string: urlString)
let data = NSData(contentsOfURL: url!)
do {
let json = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers)
for imageArray in json as! [AnyObject] {
imageArrays.append((imageArray as? [String])!)
}
} catch {
print("Error")
}
index += 1
}
addImagesToGyms()
}
func addImagesToGyms() {
var index = 0;
for array in imageArrays {
var dictionary = gyms[index] as! [String:AnyObject]
dictionary["images"] = array
gyms[index] = dictionary
index += 1
}
}
func changeSelectedSegmentIndex() {
let segmentTouched = segmentedControl?.selectedSegmentIndex
if segmentTouched == 0 {
sortAlphabetically()
} else if segmentTouched == 1 {
sortReverseAlphabetically()
} else if segmentTouched == 2 {
sortByRatingAscending()
} else {
sortByDistanceAscending()
}
}
func sortAlphabetically() {
gyms.sortInPlace{
(($0 as! Dictionary<String, AnyObject>)["name"] as? String) < (($1 as! Dictionary<String, AnyObject>)["name"] as? String)
}
tableView.reloadData()
}
func sortReverseAlphabetically() {
gyms.sortInPlace{
(($0 as! Dictionary<String, AnyObject>)["name"] as? String) > (($1 as! Dictionary<String, AnyObject>)["name"] as? String)
}
tableView.reloadData()
}
func sortByRatingAscending() {
// TODO: Sort by rating
}
func sortByDistanceAscending() {
gyms.sortInPlace{
(($0 as! Dictionary<String, AnyObject>)["distance"] as? Double) < (($1 as! Dictionary<String, AnyObject>)["distance"] as? Double)
}
tableView.reloadData()
}
func showMapView() {
self.performSegueWithIdentifier("displayMapSegue", sender: self.navigationController)
}
// MARK: - Table view data source
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return gyms.count
}
override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return 131
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("gymCell", forIndexPath: indexPath) as! GymListTableViewCell
let dictionary = gyms[indexPath.row]
let addressDictionary = dictionary["address"]
let street = addressDictionary!!["streetAddress"] as! String
let city = addressDictionary!!["city"] as! String
let state = addressDictionary!!["state"] as! String
let zipInt = addressDictionary!!["zipCode"] as! Int
let zipCode = String(zipInt)
let addressString = String("\(street) " + "\(city), " + "\(state) " + "\(zipCode)")
cell.backgroundColor = UIColor.clearColor()
cell.gymNameLabel.text = dictionary["name"] as? String
cell.gymAddressLabel.text = addressString
let miles = dictionary["distance"] as! Double
let milesString = String(format: "%.1f miles", miles)
let milesLabelString = milesString
cell.milesLabel.text = milesLabelString
let gymImages = dictionary["images"] as! [String]
if gymImages.count > 0 {
let firstImageURL = gymImages[0] as String
cell.cellImageView.sd_setImageWithURL(NSURL(string: firstImageURL))
}
return cell
}
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
let dictionary = gyms[indexPath.row]
if dictionary["name"] as? String != nil {
self.gymName = dictionary["name"] as? String
}
let cell = tableView.cellForRowAtIndexPath(indexPath) as! GymListTableViewCell
self.gymAddress = cell.gymAddressLabel.text
if dictionary["phone"] as? String != nil {
self.gymPhoneNumber = dictionary["phone"] as? String
}
if dictionary["website"] as? String != nil {
self.gymWebsite = dictionary["website"] as? String
}
if dictionary["id"] as? String != nil {
self.gymID = dictionary["id"] as? String
}
if dictionary["latitude"] as? String != nil {
self.gymLatitude = dictionary["latitude"] as? String
}
if dictionary["longitude"] as? String != nil {
self.gymLongitude = dictionary["longitude"] as? String
}
self.performSegueWithIdentifier("detailFromListSegue", sender: self.navigationController)
}
// MARK: - Navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "detailFromListSegue" {
let gymDetailVC = segue.destinationViewController as! DetailTableViewController
if self.gymName != nil {
gymDetailVC.gymName = self.gymName
} else {
gymDetailVC.gymName = nil
}
if self.gymAddress != nil {
gymDetailVC.gymAddress = self.gymAddress
} else {
gymDetailVC.gymAddress = nil
}
if self.gymPhoneNumber != nil {
gymDetailVC.gymPhoneNumber = self.gymPhoneNumber
} else {
gymDetailVC.gymPhoneNumber = nil
}
if self.gymWebsite != nil {
gymDetailVC.gymWebsite = self.gymWebsite
} else {
gymDetailVC.gymWebsite = nil
}
if self.gymID != nil {
gymDetailVC.gymID = self.gymID!
} else {
// gymDetailVC.gymID = nil
}
if self.gymLatitude != nil {
gymDetailVC.gymLatitude = self.gymLatitude!
}
if self.gymLongitude != nil {
gymDetailVC.gymLongitude = self.gymLongitude!
}
}
}
}

Answer 1

numberOfRowsInSection should be returning gymImages.count if it isn't already.
Then as a safeguard you can always do
if indexPath.row < gymImages.count {
}
before accessing the content in cellForRowAtIndexPath