UI freezes in table view - ios

Question

My tableView freezes while reloading with rows more than 600. is there any solution for that.I am getting data in background thread and try to reload my table in main thread but still the issue is same.
this is my code in cellForRow..
if (![currentUID isEqualToString:[chatDict valueForKey:#"sender"]]) {
identifier = #"onlyRightChat";
}else{
identifier = #"onlyLeftChat";
}
UITableViewCell *cell ;
cell= [tableView dequeueReusableCellWithIdentifier:identifier ];
NSString *userName;
if ([chatDict valueForKey:#"sender_last_name"]) {
userName = [NSString stringWithFormat:#"%# %#",[chatDict valueForKey:#"sender_first_name"],[chatDict valueForKey:#"sender_last_name"]];
}else{
userName = [NSString stringWithFormat:#"%#",[chatDict valueForKey:#"sender_first_name"]];
}
NSString *str ;
if (![currentUID isEqualToString:[chatDict valueForKey:#"sender"]]) {
str = [NSString stringWithFormat:#"%#:\n%#",userName,[[Utils sharedObject] convertUnicodeToEmoji:[chatDict valueForKey:#"text"]]];
}else{
str = [NSString stringWithFormat:#"You:\n%#",[[Utils sharedObject] convertUnicodeToEmoji:[chatDict valueForKey:#"text"]]];
}
CGRect labelSize =[self getRectForString:str];
if (cell == nil) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:identifier];
}
cell.selectionStyle = UITableViewCellSelectionStyleNone;
TTTAttributedLabel *lbl = (TTTAttributedLabel *)[cell.contentView viewWithTag:5111];
UIView *lblBgView = (UIView *)[cell.contentView viewWithTag:5113];
UIView *bgView = (UIView *)[cell.contentView viewWithTag:5115];
UILabel *timeLbl = (UILabel *)[cell.contentView viewWithTag:5114];
UIImageView *userImgView = (UIImageView *)[cell.contentView viewWithTag:5116];
UILabel *onlineIcon = (UILabel *)[cell.contentView viewWithTag:onlineStatusTag];
onlineIcon.layer.cornerRadius = onlineIcon.frame.size.height/2.0;
onlineIcon.clipsToBounds = YES;
lbl.backgroundColor = [UIColor clearColor];
lbl.enabledTextCheckingTypes = NSTextCheckingTypeLink|NSTextCheckingTypePhoneNumber|NSTextCheckingTypeAddress;
lbl.delegate = self;
if (![currentUID isEqualToString:[chatDict valueForKey:#"sender"]]) {
lbl.linkAttributes = #{NSForegroundColorAttributeName:[UIColor colorWithRed:91/255.0f green:135/255.0f blue:198/255.0f alpha:1.0] ,NSUnderlineStyleAttributeName: #(NSUnderlineStyleSingle)};//[UIColor colorWithRed:119/255.0f green:195/255.0f blue:66/255.0f alpha:1.0]
}else{
lbl.linkAttributes = #{NSForegroundColorAttributeName:[UIColor colorWithRed:194/255.0f green:228/255.0f blue:255/255.0f alpha:1.0] ,NSUnderlineStyleAttributeName: #(NSUnderlineStyleSingle)};//[UIColor colorWithRed:119/255.0f green:195/255.0f blue:66/255.0f alpha:1.0]
}
if ([currentUID isEqualToString:[chatDict valueForKey:#"sender"]]) {
onlineIcon.hidden = YES;
}else{
onlineIcon.hidden = NO;
NSString *status = [chatDict valueForKey:#"status"];
if(status){
if([status isEqualToString:#"online"]){
onlineIcon.backgroundColor = [UIColor colorWithRed:81/255.0 green:217/255.0 blue:93/255.0 alpha:1.0];
}else if([status isEqualToString:#"offline"]){
onlineIcon.backgroundColor = [UIColor yellowColor];
}else{
onlineIcon.backgroundColor = [UIColor colorWithRed:214/255.0 green:103/255.0 blue:101/255.0 alpha:1.0];
}
}else{
onlineIcon.backgroundColor = [UIColor yellowColor];
}
}
userImgView.layer.cornerRadius = userImgView.frame.size.height/2;
userImgView.clipsToBounds = YES;
[userImgView sd_setImageWithURL:[NSURL URLWithString:[chatDict valueForKey:#"sender_picture"]]placeholderImage:[UIImage imageNamed:#"default_avatar"]];
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(userImageViewTap:)];
tapGesture.numberOfTapsRequired = 1;
userImgView.userInteractionEnabled = YES;
[userImgView addGestureRecognizer:tapGesture];
// NSLog(#"cell.frame.size.width %f",cell.frame.size.width);
float width = cell.frame.size.width;
float height = cell.frame.size.height;
if (![currentUID isEqualToString:[chatDict valueForKey:#"sender"]])
{
bgView.frame = CGRectMake(width- labelSize.size.width-31-20-35,0,labelSize.size.width+31+20,cell.frame.size.height);
lblBgView.frame = CGRectMake(0,10,bgView.frame.size.width-15,labelSize.size.height+10);
lbl.frame = CGRectMake(8, 0, lblBgView.frame.size.width-16, labelSize.size.height+10);
timeLbl.frame = CGRectMake(width-170,height-25, 120,fontSize);
timeLbl.textAlignment = NSTextAlignmentRight;
}else{
bgView.frame = CGRectMake(35,0,labelSize.size.width+31+20,cell.frame.size.height);
lblBgView.frame = CGRectMake(15,10,bgView.frame.size.width-15,labelSize.size.height+10);
lbl.frame = CGRectMake(8, 0, lblBgView.frame.size.width-16, labelSize.size.height+10);
timeLbl.frame = CGRectMake(55,height-25, 120,fontSize);
timeLbl.textAlignment = NSTextAlignmentLeft;
}
NSDate* dateComment = [[Utils sharedObject] StringToDate:[chatDict valueForKey:#"created_at"] withFormat:#"yyyy-MM-dd'T'HH:mm:ss.SSSZZZZ"];
timeLbl.text = [[Utils sharedObject] relativeTimestamp:dateComment];
timeLbl.font = [UIFont fontWithName:#"Lato-Regular" size:fontSize-3.0];
lblBgView.layer.cornerRadius = 8.0f;
lblBgView.clipsToBounds = YES;
lbl.layer.cornerRadius = 8.0f;
lbl.font = [UIFont fontWithName:#"Lato-Regular" size:fontSize];
lbl.numberOfLines = 0;
lbl.clipsToBounds = YES;
if (str!=(id)[NSNull null])
{
if (![currentUID isEqualToString:[chatDict valueForKey:#"sender"]]) {
lbl.text = str;
}else{
NSDictionary *attrDict = #{ NSFontAttributeName : [UIFont fontWithName:#"Lato-Regular" size:fontSize], NSForegroundColorAttributeName : [UIColor colorWithRed:146/255.0 green:183/255.0 blue:201/255.0 alpha:1.0]};
NSMutableAttributedString *attrString = [[NSMutableAttributedString alloc] initWithString:#"You:\n" attributes: attrDict];
NSDictionary *attrDict1 = #{ NSFontAttributeName : [UIFont fontWithName:#"Lato-Regular" size:fontSize]};
NSMutableAttributedString *attrString1 = [[NSMutableAttributedString alloc] initWithString:[[Utils sharedObject] convertUnicodeToEmoji:[chatDict valueForKey:#"text"]] attributes: attrDict1];
[attrString appendAttributedString:attrString1];
lbl.text = str;
lbl.textColor = [UIColor whiteColor];
}
}else{
lbl.text= #"";
}
return cell;
}
and reload call from method..
-(void)getChatTextFromLocalDB{
// [self showLoadingView];
NSString *databaseKey = [NSString stringWithFormat:#"%#-%#",[self.m_dictInfo valueForKey:#"rid"],[[NSUserDefaults standardUserDefaults] objectForKey:#"rid"]];
NSString *localDBPath=[NSHomeDirectory() stringByAppendingPathComponent:#"Documents/GroupChat.plist"];
NSMutableDictionary *root = [[[NSMutableDictionary alloc] initWithContentsOfFile:localDBPath] mutableCopy];
NSMutableArray *chatDictAry = [root objectForKey:databaseKey];
NSString *localDBPath1=[NSHomeDirectory() stringByAppendingPathComponent:#"Documents/GeoConnectChat.plist"];
NSMutableDictionary *root1 = [[[NSMutableDictionary alloc] initWithContentsOfFile:localDBPath1] mutableCopy];
NSMutableArray *temp = [root1 objectForKey:#"chatDeleted"];
NSSortDescriptor *sorter = [[NSSortDescriptor alloc] initWithKey:#"created_at" ascending:YES];
NSArray *sorters = [[NSArray alloc] initWithObjects:sorter, nil];
NSArray *sortedArray = [chatDictAry sortedArrayUsingDescriptors:sorters];
NSString *lastMsgRid;
[chatDictAry removeAllObjects];
[chatDictAry addObjectsFromArray:sortedArray];
if(chatDictAry.count||[temp containsObject:databaseKey ]){
[self.chatArray removeAllObjects];
for (NSDictionary *dict in chatDictAry) {
if(!([g_Delegate.grpBlockByMeList containsObject:[dict valueForKey:#"sender"]]||[g_Delegate.grpBlockMeList containsObject:[dict valueForKey:#"sender"]])){
[self.chatArray addObject:dict];
if([dict valueForKey:#"rid"])
lastMsgRid = [dict valueForKey:#"rid"] ;
[self.usersArray addObject:[dict valueForKey:#"sender"]];
}
}
[root writeToFile:localDBPath atomically:YES];
dispatch_async(dispatch_get_main_queue(), ^(void){
[self hideLoadingView];
});
if (self.chatArray.count) {
if(tablePositionTop){
CGSize beforeContentSize = self.chatTableView.contentSize;
[self.chatTableView reloadData];
CGSize afterContentSize = self.chatTableView.contentSize;
CGPoint afterContentOffset = self.chatTableView.contentOffset;
CGPoint newContentOffset = CGPointMake(afterContentOffset.x, afterContentOffset.y + afterContentSize.height - beforeContentSize.height);
self.chatTableView.contentOffset = newContentOffset;
}
else{
[self.chatTableView reloadData];
int64_t delayInSeconds = 0.2f;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
if(actualSelf){
[self.chatTableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:[self.chatArray count]-1 inSection:0] atScrollPosition:UITableViewScrollPositionBottom animated:YES];
}
});
}
[self getUsersOnlineStatus];
if (isFirstTime) {
isFirstTime = NO;
[self getRemainingListFromServerWithLastMsgId:lastMsgRid];
}else{
// [self hideLoadingView];
}
}else{
[self hideLoadingView];
}
}
else
{
if (isFirstTime) {
isFirstTime = NO;
[self showLoadingView];
[self getAllMessages];
}
}
}

Answer 1

I suggest you watch Session 211 of WWDC 2012, Building Concurrent User Interfaces and apply the concepts there. This features cells whose contents are independently queried and rendered.
The basic concept is as follows:
1. In tableView:cellForRowAtIndexPath, a cell is instantiated.
2. In the same method, an operation for retrieving the data to populate the cell is created and stored into a dictionary. A reference to the cell is passed to the operation. The operation has a completion handler that populates the cell and removes the operation from the dictionary.
3. Before the cell is returned from the method, the operation is added to an operation queue.
4. In tableView:didEndDisplayingCell:forRowAtIndexPath, operations for cells that have moved off-screen are cancelled and removed from the dictionary.