UITableView scroll freezes when scrolling fast - ios

Question

I am using custom tableview cells in a tableview. The data is loaded from the server and height calculation of that particular cell is done inside the cell only.
<iframe width="560" height="315" src="https://www.youtube.com/embed/h-FjYkSBuNM" frameborder="0" allowfullscreen></iframe>
I am attaching the code for tableview cell for row at indexpath, custom cell method and code for get request.
class QuesAnsFeedTableViewCell: UITableViewCell {
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
setup()
}
override func layoutSubviews() {
super.layoutSubviews()
self.questionLabel.preferredMaxLayoutWidth = questionLabel.frame.width
self.answerLabel.preferredMaxLayoutWidth = answerLabel.frame.width
super.layoutSubviews()
}
func setup(){
topLeftLabel = UILabel()
topLeftLabel.font = UIFont(name: regularFont, size: 12)
topLeftLabel.text = "Yesterday"
topLeftLabel.textColor = CommonFunctions.hexStringToUIColor(hex: lightGray)
topRightLabel = UILabel()
topRightLabel.font = UIFont(name: regularFont, size: 12)
topRightLabel.textColor = CommonFunctions.hexStringToUIColor(hex: lightGray)
topRightLabel.text = ""
topRightLabel.textAlignment = .right
questionLabel = UILabel()
questionLabel.font = UIFont(name: mediumFont, size: 14)
questionLabel.text = "First Ques Comes Here and ans will be below this question"
questionLabel.numberOfLines = 0
questionLabel.lineBreakMode = .byWordWrapping
userImageView = UIImageView()
userImageView.backgroundColor = .purple
userImageView.layer.cornerRadius = CGFloat(sidePadding)/2
userImageView.clipsToBounds = true
userNameLabel = UILabel()
userNameLabel.font = UIFont(name: regularFont, size: 12)
userNameLabel.text = ""
answerLabel = UILabel()
answerLabel.font = UIFont(name: regularFont, size: 14)
answerLabel.text = ""
answerLabel.numberOfLines = 0
answerLabel.lineBreakMode = .byWordWrapping
viewOtherAnswerLabel = UILabel()
viewOtherAnswerLabel.font = UIFont(name: mediumFont, size: 12)
viewOtherAnswerLabel.text = ""
viewOtherAnswerLabel.textAlignment = .center
viewOtherAnswerLabel.textColor = CommonFunctions.hexStringToUIColor(hex: lightGray)
writeAnswerLabel = UILabel()
writeAnswerLabel.font = UIFont(name: mediumFont, size: 14)
writeAnswerLabel.backgroundColor = CommonFunctions.hexStringToUIColor(hex: crispBlue)
writeAnswerLabel.text = "Write Answer"
writeAnswerLabel.textAlignment = .center
writeAnswerLabel.textColor = .white
tapGesture = UITapGestureRecognizer(target: self, action: #selector(self.tappedCell(sender:)))
tapGesture.numberOfTapsRequired = 1
self.addGestureRecognizer(tapGesture)
// self.addSubview(likeButton)
// self.addSubview(descriptionLabel)
}
func updateData(data:NSDictionary) -> CGFloat{
if let viewCount = data["vc"] {
topRightLabel.text = "\(viewCount) read"
}
if let ques = data["q"] as? String{
topLeftLabel.frame = CGRect(x:sidePadding/2, y: 2*sidePaddingForCollectionCells, width: screenWidth/2-sidePadding, height: Int(CommonFunctions.calculateHeight(inString: topLeftLabel.text!, forFont: topLeftLabel.font, andWidthOfLabel: CGFloat(screenWidth/2))))
topRightLabel.frame = CGRect(x: screenWidth/2, y: 2*sidePaddingForCollectionCells, width: screenWidth/2-sidePadding/2, height: Int(topLeftLabel.frame.height))
let newHeight = CommonFunctions.calculateHeight(inString: ques,forFont:questionLabel.font,andWidthOfLabel:questionLabel.frame.width)
questionLabel.frame = CGRect(x:sidePadding/2 ,y: Int(topLeftLabel.frame.maxY)+sidePaddingForCollectionCells,width: screenWidth - sidePadding, height: Int(ceil(Float(newHeight))))
questionLabel.text = ques
self.addSubview(topLeftLabel)
self.addSubview(topRightLabel)
self.addSubview(questionLabel)
// questionLabel.attributedText = CommonFunctions.justifiedText(string: ques)
}
if let user = data.object(forKey: "user") as? NSDictionary{
if let usrName = user.value(forKey: "name"){
userNameLabel.text = "\(usrName)"
}
if let imgLink = user["image"] as? String{
if let url = URL(string: imgLink){
userImageView.sd_setImage(with: url,placeholderImage:#imageLiteral(resourceName: "placeholderImage"))
}
}
}
if let otherAnswer = data.value(forKey: "cc") {
viewOtherAnswerLabel.text = "View Other Answer \(otherAnswer)"
}
if let ans = data.value(forKey: "comt") as? String{
answered = true
userImageView.frame = CGRect(x: sidePadding/2, y: Int(questionLabel.frame.maxY)+2*sidePaddingForCollectionCells, width: sidePadding, height: sidePadding)
userNameLabel.frame = CGRect(x: 3*sidePadding/2+2*sidePaddingForCollectionCells, y:Int(questionLabel.frame.maxY)+sidePaddingForCollectionCells, width: screenWidth-2*sidePadding, height: Int(topLeftLabel.frame.height))
let newHeight = CommonFunctions.calculateHeight(inString: ans,forFont:answerLabel.font,andWidthOfLabel:answerLabel.frame.width)
let frame = CGRect(x: 3*sidePadding/2+2*sidePaddingForCollectionCells, y:Int(userNameLabel.frame.maxY) + sidePaddingForCollectionCells, width: screenWidth-2*sidePadding-2*sidePaddingForCollectionCells, height: Int(ceil(Float(newHeight))))
answerLabel.frame = frame
answerLabel.text = ans
viewOtherAnswerLabel.frame = CGRect(x: 0, y: Int(answerLabel.frame.maxY)+2*sidePaddingForCollectionCells, width: screenWidth, height: 2*sidePadding/3)
self.addSubview(userImageView)
self.addSubview(userNameLabel)
self.addSubview(answerLabel)
self.addSubview(viewOtherAnswerLabel)
writeAnswerLabel.removeFromSuperview()
return viewOtherAnswerLabel.frame.maxY
}
else{
answered = false
writeAnswerLabel.frame = CGRect(x: 0, y:Int(questionLabel.frame.maxY) + 2*sidePaddingForCollectionCells, width: screenWidth, height: sidePadding)
self.addSubview(writeAnswerLabel)
userImageView.removeFromSuperview()
userNameLabel.removeFromSuperview()
answerLabel.removeFromSuperview()
viewOtherAnswerLabel.removeFromSuperview()
return writeAnswerLabel.frame.maxY
}
}
TableView Code
class GenericView: UIView ,UITableViewDelegate,UITableViewDataSource {
var tableView:UITableView!
var viewFrame = CGRect()
var parentView = ""
var discussViewHeight = [Int:CGFloat]()
var nextUrlPath = ""
var currentUrlPath = ""
private var sliderLabelsText = ["Favourites","Sign In"]
private var tableBlocks = [NSDictionary]()
override init(frame: CGRect) {
super.init(frame: frame)
viewFrame = frame
setup()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
if viewFrame != CGRect() {
setup()
}
}
public func updateView(){
viewFrame = self.frame
tableView.frame = (viewFrame)
getRequest()
}
func getRequest(){
currentUrlPath = baseUrl+nextUrlPath
if parentView == discussView{
// let url = baseUrl + nextUrlPath
Alamofire.request(currentUrlPath).responseJSON { response in
if let dict = response.result.value as? [String:AnyObject]{
if (dict["msc"]) as? String == "700", let blocks = dict["blocks"] as? NSArray{
self.nextUrlPath = (dict["next"] as? String ?? "")
for block in blocks{
if let blk = block as? NSDictionary{
if blk.value(forKey: "ty") as? String == "qa"{
self.tableBlocks.append(blk)
}
appDelegate.tableBlocks.append(blk)
}
}
DispatchQueue.main.async(execute: { () -> Void in
self.refreshControl.endRefreshing()
self.tableView.reloadData()
})
}
else{
DispatchQueue.main.async(execute: { () -> Void in
self.currentUrlPath = ""
self.getRequest()
})
}
}
}
return
}
}
func setup(){
backgroundColor = UIColor.white
tableView = UITableView(frame: viewFrame, style: .grouped)
tableView.delegate = self
tableView.dataSource = self
self.addSubview(tableView)
registerCells()
}
//MARK: TableView DataSource Methods
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if parentView == discussView{
return 1
}
return 0
}
func numberOfSections(in tableView: UITableView) -> Int {
if parentView == discussView{
return tableBlocks.count
}
return 0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if (parentView == discussView){
var cell:QuesAnsFeedTableViewCell? = tableView.dequeueReusableCell(withIdentifier: quesAnsFeedViewCellIdentifier, for: indexPath) as? QuesAnsFeedTableViewCell
if (cell == nil){
cell = QuesAnsFeedTableViewCell(style: .default, reuseIdentifier: quesAnsFeedViewCellIdentifier)
}
cell?.selectionStyle = .none
discussViewHeight[indexPath.section] = (cell?.updateData(data: tableBlocks[indexPath.section]))!
cell?.setNeedsLayout()
cell?.layoutIfNeeded()
return cell!
}
return UITableViewCell()
}
//MARK: TableView Delegate Methods
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
if parentView == discussView{
return discussViewHeight[indexPath.section] ?? 0
}
return 0
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
if parentView == discussView{
return sectionHeaderView
}
return UIView()
}
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
if parentView == discussView && indexPath.section+5 > tableBlocks.count{
if currentUrlPath != baseUrl + nextUrlPath{
getRequest()
}
}
}
}
I have deleted some code from classes just to keep the size of question small.
The call for next fetch will depend on the indexpath of cell which is currently being displayed and the function which fetches the content from server will be getRequest().
Any help is greatly appreciated