swift: Completion handler - ios

Question

So, I have method loadData() which download datas from parse.com
And I should present all images show in table view.
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("ReusableCell", forIndexPath: indexPath) as! LeaguesTableViewCell
loadData { (success) in
if success {
cell.leagueImage.image = UIImage(data: self.leaguesImage[indexPath.row])
cell.leagueNameLabel.text = self.leagues[indexPath.row]["name"] as? String
} else {
cell.leagueNameLabel.text = "Wait"
}
}
return cell
}
Its didn't work. I call my function in viewDidLoad() but its not correct too, table view is empty.
Cuz my array is empty
My

Answer 1

The basic procedure for loading data into a UITableView is:
Load the data
Reload the table view
Return the number of sections in numberOfSectionsInTableView: method: In your case there is only 1 section.
Return the number of rows in tableView:numberOfRowsInSection:: In your case return the number of leagues if the data is loaded. If the data is not loaded then return 1 so that the table view has at least one row to display the "Wait" message.
Create and populate the cells from the data: Use leagues and leaguesImage.
Example:
private var loaded = false
override func viewDidLoad() {
super.viewDidLoad()
loaded = false
loadData() { success in
NSOperationQueue.mainQueue().addOperationWithBlock() {
self.loaded = success
self.tableView.reloadData()
}
}
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection: Int) -> Int {
if loaded {
return leagues.count
}
else {
return 1
}
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("ReusableCell", forIndexPath: indexPath) as! LeaguesTableViewCell
if loaded {
cell.leagueImage.image = UIImage(data: self.leaguesImage[indexPath.row])
cell.leagueNameLabel.text = self.leagues[indexPath.row]["name"] as? String
}
else {
cell.leagueNameLabel.text = "Wait"
}
return cell
}

Answer 2

Try to set delegate and datasource first. If you have separate datasource other than view controller, retain it otherwise you will not get any callback.