image on tableview cell repeating due to reusability issue - ios

Question

I have a table view cell,having labels and images,on scrolling the images and labels get changed,this is due to the cell dequeue feature.I tried to resolve it by setting the imageview to nil,but it doesn't work.
The problem of repeatition is with PinImageView,that takes image from an array of images,its not with the one which takes images from URL.
-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
static NSString *cellIdentifier=#"cellIdentifier";
TripInfoListCell *cell=[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell==nil) {
cell=(TripInfoListCell *)[[[NSBundle mainBundle] loadNibNamed:#"TripInfoListCell" owner:self options:nil] firstObject];
}
cell.PinImageView.image = nil;
NSString *direction=[dict123 valueForKey:#"direction" ] ;
NSString *drive_status=[dict123 valueForKey:#"driver_or_rider"];
if((indexPath.row==totalRow-1)&&[direction isEqual:#"From"])
{
__weak TripInfoListCell *weakCell = cell;
cell.PinImageView.image=[UIImage imageNamed:#"pin7#2x.png"];
cell.userNameLabel.text=loggedUser.profile_name;
cell.riderDriverSlNo.text=#"Driver";
if([drive_status isEqual:#"Ride"])
{
cell.riderDriverSlNo.text=#"Driver";
cell.userNameLabel.text=#"Driver"; //In case of "Rider" "From" name in the last row
}
else{
cell.availabiltyInfoLabel.text=#"You";
}
NSString *imagePic = [[NSUserDefaults standardUserDefaults] objectForKey:#"user_image"];
NSURLRequest *request=[NSURLRequest requestWithURL:[NSURL URLWithString:imagePic]];
[cell.userImageView setImageWithURLRequest:request placeholderImage:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
weakCell.userImageView.image=image;
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
NSLog(#"%#",error);
}];
}
else if((indexPath.row==totalRow-1)&&[direction isEqual:#"To"])
{
cell.PinImageView.image=[UIImage imageNamed:#"pin7#2x.png"];
cell.userNameLabel.text=[_tripDetails objectForKey:#"park_name"];
NSString *image=[NSString stringWithFormat:#"%#",[dict123 objectForKey:#"parkBannerImageUrl"]];
[[ImageHandler sharedInstance] getImageFromURL:image withCompletion:^(UIImage *image) {
if (image) {
[cell.userImageView setImage:image];
}
}];
}
else
if ([tableGoersList count] > indexPath.row)
{
NSDictionary *goersInfo=[tableGoersList objectAtIndex:indexPath.row];
[[NSUserDefaults standardUserDefaults]setObject:[goersInfo valueForKey:#"user_image_url"] forKey:#"user_image"];
[[NSUserDefaults standardUserDefaults]synchronize];
__weak TripInfoListCell *weakCell = cell;
NSURLRequest *request=[NSURLRequest requestWithURL:[NSURL URLWithString:goersInfo[#"user_image_url"]]];
[cell.userImageView setImageWithURLRequest:request placeholderImage:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
weakCell.userImageView.image=image;
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
NSLog(#"%#",error);
}];
if((indexPath.row==0)&&[direction isEqual:#"To"]) {
if([drive_status isEqual:#"Drive"]){
cell.riderDriverSlNo.text=#"Driver";
cell.PinImageView.image=[UIImage imageNamed:#"pin1#2x.png"];
cell.userNameLabel.text=loggedUser.profile_name;
cell.availabiltyInfoLabel.text=#"You";
}
else{
}
}
else if((indexPath.row==0)&&[direction isEqual:#"From"]) {
if([drive_status isEqual:#"Drive"])
{
cell.PinImageView.image=[UIImage imageNamed:#"pin1#2x.png"];
cell.userNameLabel.text=[_tripDetails objectForKey:#"park_name"];
cell.riderDriverSlNo.text=#"";
cell.availabiltyInfoLabel.text=#"";
NSString *image=[NSString stringWithFormat:#"%#",[dict123 objectForKey:#"parkBannerImageUrl"]];
[[ImageHandler sharedInstance] getImageFromURL:image withCompletion:^(UIImage *image) {
if (image) {
[cell.userImageView setImage:image];
}
}];
}
else{
NSLog(#"rider from");
cell.riderDriverSlNo.text=#"";
}
}
else{
imageNameArray = [[NSArray alloc] initWithObjects:#"pin2#2x.png", #"pin3#2x.png", #"pin4#2x.png", #"pin5#2x.png", #"pin6#2x.png",#"pin8#2x.png",#"pin9#2x.png", nil];
NSString* nameStr=[goersInfo valueForKey:#"name"];
NSArray * nameStrArray = [nameStr componentsSeparatedByString: #"'s"];
nameStr=[nameStrArray objectAtIndex:0];
cell.riderDriverSlNo.text=[NSString stringWithFormat:#"Rider %ld",(long)indexPath.row];
index = [TripInfoVC ifNameExists:_arrName Name:nameStr];
if(index == 0)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:0]];
[_arrName addObject:nameStr];
}
if(index == 1)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:1]];
}
if(index == 2)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:2]];
}
if(index == 3)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:3]];
}
if(index == 4)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:4]];
}
if(index == 5)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:5]];
}
if(index == 6)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:6]];
}
if(index == 7)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:0]];
}
if(index == 8)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:1]];
}
if(index == 9)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:2]];
}
if(index == 10)
{
cell.PinImageView.image=[UIImage imageNamed:[imageNameArray objectAtIndex:3]];
}
} // this pinImageView is the pin image which is repeated on scrolling
return cell;
}
Please help me solving this issue.

Answer 1

you may be faces the closure collision. when you declare completion block
[cell.userImageView setImageWithURLRequest:request placeholderImage:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
weakCell.userImageView.image=image;
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
NSLog(#"%#",error);
}];
weakCell is the pointer to cell object that was requested by UITableView delegate. it maybe reused later when you scroll the table and at that moment your completion block may actually be invoked, because downloading
process is not immediate.
How to handle it? I would use etc. UITableViewCell.tag property for identification of what exactly image I requested at the moment when cell was required and does it match the image I am trying to put to that cell when completion block is running. maybe some other downloading was fired later and overwritten tag property.

Answer 2

You have to implement load images in the fly or lazy loading by adding your code into delegate method of UICollection cellForRowAtIndexPath method on operation queue.
And, if you are doing something on UI that you have placed inside main thread, here is another example:
Lazy loading images in UICollectionView with SDWebImageManager