Swift - Populating UITableView with data from API - ios

Question

I am trying to set up a feed page with a UITableView, retrieving all the JSON data from Node.js API.
Looks like it it is working, but it is very slow and sometimes does not retrieve all the images. Is there a way to make it work completely, and to optimize the code?
import UIKit
class homeViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet weak var tableView: UITableView!
var jsonData : [NSDictionary] = [NSDictionary]()
var imageUrls: NSDictionary = NSDictionary()
var urlsArray: [NSURL]! = [NSURL]()
override func viewDidLoad() {
super.viewDidLoad()
self.tableView.reloadData()
let qualityOfServiceClass = QOS_CLASS_BACKGROUND
let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
dispatch_async(backgroundQueue, {
println("This is run on the background queue")
self.refreshData()
self.getImage()
dispatch_async(dispatch_get_main_queue(), { () -> Void in
println("This is run on the main queue, after the previous code in outer block")
self.tableView.reloadData()
})
})
}
override func viewWillAppear(animated: Bool) {
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return jsonData.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var type = jsonData[indexPath.row]["type"] as! Int
if type == 1 {
println("Type= \(type)")
let cell1 : cellTableViewCell = self.tableView.dequeueReusableCellWithIdentifier("cell") as! cellTableViewCell
//If images url are retrieved, load them. Otherwise, load the placeholders
if self.urlsArray.isEmpty == false {
println("Tiè: \(self.urlsArray[indexPath.row])")
if let data = NSData(contentsOfURL: self.urlsArray[indexPath.row]) {
cell1.profileImg?.image = UIImage(data: data)
}
} else {
cell1.profileImg?.image = UIImage(named: "placeholder.png")
}
cell1.testLbl.text = (self.jsonData[indexPath.row]["author"] as? String)!
return cell1
} else {
let cell2 : cell2TableViewCell = self.tableView.dequeueReusableCellWithIdentifier("cell2") as! cell2TableViewCell
return cell2
}
}
func refreshData() {
let requestURL = NSURL(string:"http://adall.ga/api/feeds/author/mat/0")!
var request = NSMutableURLRequest(URL: requestURL)
request.HTTPMethod = "GET"
request.addValue(userToken, forHTTPHeaderField: "tb-token")
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request) {
data, response, error in
println(response)
var dataString = NSString(data: data, encoding: NSUTF8StringEncoding)
println(dataString)
//let jsonResult : NSDictionary = (NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers, error: nil) as? NSDictionary)!
//jsonData = (NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers , error: nil) as? NSArray)!
self.jsonData = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.AllowFragments, error: nil) as! [NSDictionary]
}
task.resume()
var index: Int
for index = 0; index < 10000; ++index {
print("Index: \(index), Task state: \(task.state)")
}
}
func getImage() {
var i = 0
for jsonSingleData in jsonData {
let author = jsonSingleData["author"] as! String
let requestURL2 = NSURL(string: "http://adall.ga/api/users/" + author + "/image")!
println("request: \(requestURL2)")
var request2 = NSMutableURLRequest(URL: requestURL2)
request2.HTTPMethod = "GET"
request2.addValue(userToken!, forHTTPHeaderField: "tb-token")
let session2 = NSURLSession.sharedSession()
let task2 = session2.dataTaskWithRequest(request2) {
data, response, error in
println("response= \(response)")
var dataString = NSString(data: data, encoding: NSUTF8StringEncoding)
println(dataString)
self.imageUrls = (NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as! NSDictionary)
//check if exists
let imageUrl = self.imageUrls["url"] as! String
let url = NSURL(string: "http://" + imageUrl)
self.urlsArray.append(url!)
println(self.urlsArray)
}
task2.resume()
}
}

Answer 1

Hi for loading images you can use SDWebImage it will take care of all the heavy lifting and caching for you. here's how:
// Here we use the new provided sd_setImageWithURL: method to load the web image
[cell.imageView sd_setImageWithURL:[NSURL URLWithString:#"http://www.domain.com/path/to/image.jpg"]
placeholderImage:[UIImage imageNamed:#"placeholder.png"]
completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {... completion code here ...}];
Here's a Swift example