Swift - UITableView lags with images - ios

Question

My problem is when I scroll down my UITableView, it looks too laggy. The images grab from facebook.
My code
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("UserCell", forIndexPath: indexPath) as UITableViewCell
let user = users[indexPath.row] as User //2
if let nameLabel = cell.viewWithTag(100) as? UILabel { //3
nameLabel.text = user.name
}
if let dateCreatedLabel = cell.viewWithTag(101) as? UILabel {
dateCreatedLabel.text = user.distance
}
if let profilePictureView = cell.viewWithTag(103) as? UIImageView {
if let url = NSURL(string: "https://graph.facebook.com/\(user.profilePhoto)/picture?type=large") {
if let data = NSData(contentsOfURL: url){
profilePictureView.contentMode = UIViewContentMode.ScaleAspectFit
profilePictureView.image = UIImage(data: data)
}
}
}
return cell
}
Please advice how to make it smooth.

Answer 1

OMG, never do like this not only in scrolling controls, but in general UI also:
data = NSData(contentsOfURL: url)
Thats why you table lags, and you lucky enougth with fast internet. If you connection will be slow, you app will hang, may be forever. ALWAYS do network asyncronously!
Also, when you make you network async, your tableView will still lag here:
UIImage(data: data)
And even here if you have many controls in your cell:
cell.viewWithTag(101)
So, use some library to download images, this is surprisingly not so easy task as it seems to be, you will not do it right yourself according to you experience (as I can see it).
Make separate class for you cell and use IB to connect outlets.
Try AFNetworking, it has category for UIImageView to download images.

Answer 2

I already found the answer. Use Haneke instead NSData.
import Haneke
/* .. */
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("UserCell", forIndexPath: indexPath) as UITableViewCell
let user = users[indexPath.row] as User //2
if let nameLabel = cell.viewWithTag(100) as? UILabel { //3
nameLabel.text = user.name
}
if let dateCreatedLabel = cell.viewWithTag(101) as? UILabel {
dateCreatedLabel.text = user.distance
}
if let profilePictureView = cell.viewWithTag(103) as? UIImageView {
if let url = NSURL(string: "https://graph.facebook.com/\(user.profilePhoto)/picture?type=large") {
profilePictureView.contentMode = UIViewContentMode.ScaleAspectFit
profilePictureView.hnk_setImageFromURL(url!)
}
}
return cell
}