swift3 uitableView reload makes screen blink - ios

Question

I am using UITableview and it looks similar with the feed of Instagram. The issue I have
I have a like function in each tableviewCell
when tap like button, it needs to update the screen and the screen blinks
In tableview cellForRowAt function, I have a network call to check the like and its number.
Please let me know if there is a way to avoid this blink. Should I avoid network call in this function or is there any other way?
U can see some part of my code below:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! StoryReviewTableViewCell
let review = ReviewArray[indexPath.row]
// 프로필 이미지랑 닉네임 설정
if let user = review.creator {
let nickname = user.getProperty("nickname") as! String
cell.profileName.text = nickname
if let profileURL = user.getProperty("profileURL") {
if profileURL is NSNull {
cell.profileImage.image = #imageLiteral(resourceName: "user_profile")
} else {
let url = URL(string: profileURL as! String)
DispatchQueue.main.async {
cell.profileImage.kf.setImage(with: url, placeholder: #imageLiteral(resourceName: "imageLoadingHolder"), options: [.transition(.fade(0.2))], progressBlock: nil, completionHandler: nil)
}
}
}
} else {
// 삭제된 유저의 경우
cell.profileName.text = "탈퇴 유저"
cell.profileImage.image = #imageLiteral(resourceName: "user_profile")
}
// 장소 이름
if let store = ReviewArray[indexPath.row].store {
cell.storeName.text = "장소: \(String(describing: store.name!))"
} else {
cell.storeName.text = "가게 이름"
}
// 라이크버튼 설정 - 라이크 모양은 여기서 컨트롤, delegate에서 user 라이크 컨트롤
DispatchQueue.global(qos: .userInteractive).async {
let likeStore = Backendless.sharedInstance().data.of(ReviewLikes.ofClass())
let dataQuery = BackendlessDataQuery()
let objectID = review.objectId!
let userID = UserManager.currentUser()!.objectId!
// print("objectID & userID: \(objectID) & \(userID)")
// 여기서 by가 현재 유저의 objectId이어야 하고, to는 이 리뷰의 objectId이어야 한다
dataQuery.whereClause = "by = '\(userID)' AND to = '\(objectID)'"
DispatchQueue.main.async {
likeStore?.find(dataQuery, response: { (collection) in
let likes = collection?.data as! [ReviewLikes]
// 하트를 안 눌렀을 때
if likes.count == 0 {
DispatchQueue.main.async {
cell.likeButton.setImage(#imageLiteral(resourceName: "like_bw"), for: .normal)
}
} else {
DispatchQueue.main.async {
cell.likeButton.setImage(#imageLiteral(resourceName: "like_red"), for: .normal)
}
}
}, error: { (Fault) in
print("라이크 불러오기에서 에러: \(String(describing: Fault?.description))")
})
}
// 좋아요 개수 세기
let countQuery = BackendlessDataQuery()
// to가 story의 objectID와 일치하면 땡
countQuery.whereClause = "to = '\(objectID)'"
let queryOptions = QueryOptions()
queryOptions.pageSize = 1
countQuery.queryOptions = queryOptions
DispatchQueue.global(qos: .userInteractive).async {
let matchingLikes = likeStore?.find(countQuery)
let likeNumbers = matchingLikes?.totalObjects
DispatchQueue.main.async {
if likeNumbers == 0 {
cell.likeLabel.text = "라이크 없음 ㅠ"
} else {
cell.likeLabel.text = "\(String(describing: likeNumbers!))개의 좋아요"
}
}
}
}
// 리뷰 평점 배당
cell.ratingView.value = review.rating as! CGFloat
// 리뷰 바디
cell.reviewBody.text = review.text
// 코멘트 개수 받아오기
DispatchQueue.global(qos: .userInteractive).async {
// 댓글수 찾기
let tempStore = Backendless.sharedInstance().data.of(ReviewComment.ofClass())
let reviewId = review.objectId!
let dataQuery = BackendlessDataQuery()
// 이 리뷰에 달린 댓글 모두 몇 개인지 찾기
dataQuery.whereClause = "to = '\(reviewId)'"
DispatchQueue.main.async {
tempStore?.find(dataQuery, response: { (collection) in
let comments = collection?.data as! [ReviewComment]
cell.replyLabel.text = "댓글 \(comments.count)개"
}, error: { (Fault) in
print("서버에서 댓글 얻어오기 실패: \(String(describing: Fault?.description))")
})
}
}
cell.timeLabel.text = dateFormatter.string(from: review.created! as Date)
return cell
}
U can see the button action here
#IBAction func likeButtonClicked(_ sender: UIButton) {
likeButton.isUserInteractionEnabled = false
// delegate action
delegate?.actionTapped(tag: likeButton.tag)
// image change
if sender.image(for: .normal) == #imageLiteral(resourceName: "like_bw") {
UIView.transition(with: sender, duration: 0.2, options: .transitionCrossDissolve, animations: {
sender.setImage(#imageLiteral(resourceName: "like_red"), for: .normal)
}, completion: nil)
self.likeButton.isUserInteractionEnabled = true
} else {
UIView.transition(with: sender, duration: 0.2, options: .transitionCrossDissolve, animations: {
sender.setImage(#imageLiteral(resourceName: "like_bw"), for: .normal)
}, completion: nil)
self.likeButton.isUserInteractionEnabled = true
}
}
This is part of my delegate function which reload only for the row
func changeLike(_ row: Int, _ alreadyLike: Bool, completionHandler: #escaping (_ success:Bool) -> Void) {
let selectedReview = ReviewArray[row]
let reviewId = selectedReview.objectId
// 그냥 유저 객체로 비교는 안되고 objectId로 체크를 해야 함
let objectID = Backendless.sharedInstance().userService.currentUser.objectId
let dataStore = Backendless.sharedInstance().data.of(ReviewLikes.ofClass())
// 좋아요 - alreadyLike가 true이면
if !alreadyLike {
// 객체 생성
let like = ReviewLikes()
like.by = objectID! as String
like.to = reviewId
dataStore?.save(like, response: { (response) in
DispatchQueue.main.async {
let indexPath = IndexPath(row: row, section: 0)
self.tableView.reloadRows(at: [indexPath], with: .none)
}
}

Answer 1

let cell = self.tblView.cellForRow(at: IndexPath(row: index, section: 0)) as! UITableViewCell
cell.btnLike.setImage(UIImage(named: (isReviewed! ? IMG_LIKE : IMG_UNLIKE)), for: .normal)
Just update the cell, instead of reloading whole data in the tableview.

Answer 2

Try to call data on button click instead of cellForRowAtIndexpath and use that button which clicked instead of reload data
#IBAction func likeButtonClicked(_ sender: UIButton) {
let buttonPosition:CGPoint = sender.convert(CGPointZero, to:self.tableView)
let indexPath = self.tableView.indexPathForRow(at: buttonPosition)
let cell = tableView.cellForRow(at: indexPath) as! StoryReviewTableViewCell
DispatchQueue.main.async {
likeStore?.find(dataQuery, response: { (collection) in
let likes = collection?.data as! [ReviewLikes]
// 하트를 안 눌렀을 때
if likes.count == 0 {
DispatchQueue.main.async {
cell.likeButton.setImage(#imageLiteral(resourceName: "like_bw"), for: .normal)
}
} else {
DispatchQueue.main.async {
cell.likeButton.setImage(#imageLiteral(resourceName: "like_red"), for: .normal)
}
}
}, error: { (Fault) in
print("라이크 불러오기에서 에러: \(String(describing: Fault?.description))")
})
}