My scrolling, while smooth usually, is jerky sometimes - swift

Question

The following is my code. I read using NSDateFormatters were expensive, but I'm not sure if that's what's eventually causing the problem.
Here's my code.
func tableViewOld(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!, object: PFObject!) -> UITableViewCell! {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! TableViewCell
if cell.backgroundView == nil {
cell.backgroundView = UIImageView(frame: cell.contentView.bounds)
cell.backgroundView?.contentMode = UIViewContentMode.ScaleToFill
cell.backgroundView?.clipsToBounds = true
cell.contentView.backgroundColor = UIColor.clearColor()
}
let backgroundImageView = cell.backgroundView as! UIImageView
backgroundImageView.image = UIImage(named: "nobg")
var image : UIImage = UIImage(named:"goodbg")!
cell.nopebutton.tag = indexPath.row
cell.nicebutton.tag = indexPath.row
cell.messageButton.tag = indexPath.row
cell.mText.text = object.valueForKey("text") as? String
let count = object.valueForKey("replies") as! Int
cell.replies.text = "\(count)"
cell.replies.textColor = UIColor.whiteColor()
let point = object["location"] as! PFGeoPoint
let location = CLLocation(latitude: point.latitude, longitude: point.longitude)
let currentLocation = CLLocation(latitude: currLocation!.latitude, longitude: currLocation!.longitude)
let distance = currentLocation.distanceFromLocation(location)
if distance < 50 {
// TODO: Fill
cell.locationButton.text = "Nearby"
} else {
let distanceFormatter = MKDistanceFormatter()
distanceFormatter.unitStyle = MKDistanceFormatterUnitStyle.Abbreviated
cell.locationButton.text = distanceFormatter.stringFromDistance(distance) + " away"
}
cell.layoutMargins = UIEdgeInsetsZero
let score = object.valueForKey("count") as! Int
cell.count.text = "\(score)"
if cell.count.text?.toInt() == 0
{
cell.messages.imageView?.image = UIImage(named:"0")
cell.chatbubble.image = UIImage(named:"ch")
cell.bg.image = UIImage(named: "regular")
cell.locationButton.textColor = UIColor.blackColor()
cell.mText.textColor = UIColor(red: 126.0/255, green: 126.0/255, blue: 126.0/255, alpha: 1)
cell.nicebutton!.setImage(UIImage(named:"ups"), forState: UIControlState.Normal)
cell.nopebutton!.setImage(UIImage(named:"downs"), forState: UIControlState.Normal)
cell.count.textColor = UIColor.whiteColor()
cell.time.textColor = UIColor(red: 52.0/255, green: 152.0/255, blue: 219.0/255, alpha: 1)
}
if cell.count.text?.toInt() > 0
{
cell.messages.imageView?.image = UIImage(named:"1")
cell.chatbubble.image = UIImage(named:"chg")
cell.bg.image = UIImage(named: "gtrl")
cell.time.textColor = UIColor(red: 42.0/255, green: 204.0/255, blue: 113.0/255, alpha: 1)
cell.locationButton.textColor = UIColor.blackColor()
cell.mText.textColor = UIColor(red: 42.0/255, green: 204.0/255, blue: 113.0/255, alpha: 1)
cell.count.textColor = UIColor.whiteColor()
}
if cell.count.text?.toInt() < 0
{
cell.messages.imageView?.image = UIImage(named:"-1")
cell.bg.image = UIImage(named: "ntrl")
cell.chatbubble.image = UIImage(named:"chr")
cell.locationButton.textColor = UIColor.blackColor()
cell.time.textColor = UIColor(red: 231.0/255, green: 76.0/255, blue: 50.0/255, alpha: 1)
cell.mText.textColor = UIColor(red: 231.0/255, green: 76.0/255, blue: 50.0/255, alpha: 1)
cell.count.textColor = UIColor.whiteColor()
}
if cell.count.text?.toInt() >= 100
{
cell.messages.imageView?.image = UIImage(named:"100")
cell.chatbubble.image = UIImage(named:"chb")
cell.locationButton.textColor = UIColor.blackColor()
cell.time.textColor = UIColor(red: 249.0/255, green: 194.0/255, blue: 65.0/255, alpha: 1)
cell.mText.textColor = UIColor(red: 249.0/255, green: 194.0/255, blue: 65.0/255, alpha: 1)
cell.bg.image = UIImage(named: "neutral")
cell.count.textColor = UIColor.whiteColor()
}
if let dict : NSDictionary = NSUserDefaults.standardUserDefaults().objectForKey("userNiceNopeDictionary") as? NSDictionary {
cell.nicebutton.enabled = true
cell.nopebutton.enabled = true
if let nice = dict[object.objectId] as? Bool{
if nice {
cell.nicebutton.enabled = false
}
else {
cell.nopebutton.enabled = false
}
}
}
if let user = PFUser.currentUser() {
user["createdBy"] = user.username
//user.saveInBackground()
}
let dateUpdated = object.createdAt as NSDate
let dateFormat = NSDateFormatter()
dateFormat.dateFormat = "h:mm a"
cell.time.text = (NSString(format: "%#", dateFormat.stringFromDate(dateUpdated)) as String) as String
let replycnt = object.objectForKey("replies") as! Int
if cell.count.text == "\(-10)"
{
object.deleteInBackground()
}
return cell
}
and I'm utilizing this extension.
extension NSDate
{
func hour() -> Int
{
//Get Hour
let calendar = NSCalendar.currentCalendar()
let components = calendar.components(.CalendarUnitHour, fromDate: self)
let hour = components.hour
//Return Hour
return hour
}
func minute() -> Int
{
//Get Minute
let calendar = NSCalendar.currentCalendar()
let components = calendar.components(.CalendarUnitMinute, fromDate: self)
let minute = components.minute
//Return Minute
return minute
}
func toShortTimeString() -> String
{
//Get Short Time String
let formatter = NSDateFormatter()
formatter.timeStyle = .ShortStyle
let timeString = formatter.stringFromDate(self)
//Return Short Time String
return timeString
}
}
Is there a way I can optimize this? Again this isn't constantly laggy, it only happens sometimes, but in general it seems to be fine. I'd like to to ALWAYS be fine. Again I feel as though the NSDateFormatter might be the problem, but I'm not quite sure.

Answer 1

You're doing a hell of a lot in the cellForRow method. As a comparison my cellForRow method consists of around 5 lines of code. You should look at creating a custom cell class that removes a lot of that code. With a lot of code it just makes it harder to work out what the cause of problems is.
Each section of that code configures textfields could be a new function. Just, aim for like 10 lines of code per function. If you have more, move stuff into a new function (that makes sense).
What might be causing the issue is creating the NSDateFormatter every time you use the toShortTimeString method.
In fact, I've just seen that you are creating another NSDateFormatter yourself. Creating NSDateFormatter is an expensive thing to do. You should create one as a property of the TableViewController and use that over and over instead of creating it again and again.
That seems like it could be the issue but your function is too big to read through it all. Work on fixing that too.
Number of lines needed in the function... 3.
1 to dequeue the cell.
1 to call a function to configure the cell
1 to return the cell