Jeef Jeef - 5 months ago 17
Swift Question

Swift UITableView reloadData in a closure

I believe I'm having an issue where my closure is happening on a background thread and my UITableView isn't updating fast enough. I am making a call to a REST service and in my closure i have a

tableView.reloadData()
call but it takes a few seconds for this to happen. How do I make the data reload faster (perhaps on the main thread?)

REST Query Function - using SwiftyJSON library for Decoding

func asyncFlightsQuery() {
var url : String = "http://127.0.0.1:5000/flights"
var request : NSMutableURLRequest = NSMutableURLRequest()
request.URL = NSURL(string: url)
request.HTTPMethod = "GET"

NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, networkData: NSData!, error: NSError!) -> Void in
var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil


// Parse with SwiftyJSON
let json = JSON(data: networkData)

// Empty out Results array
self.resultArray = []

// Populate Results Array
for (key: String, subJson: JSON) in json["flights"] {
print ("KEY: \(key) ")
print (subJson["flightId"])
print ("\n")

self.resultArray.append(subJson)
}

print ("Calling reloadData on table..??")
self.tableView.reloadData()


})
}


Once
self.tableView.reloadData()
is called in my debugger

Answer

UIKit isn't thread safe. The UI should only be updated from main thread:

dispatch_async(dispatch_get_main_queue()) {
    self.tableView.reloadData()
}
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