how can i display images in uitableviewcells using Asyncronous concept in ios - ios

Question

I have to show some post blogs into a UITableView. When I have retreived all web service data.
This is my sample code.
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
[UIApplication sharedApplication].networkActivityIndicatorVisible=YES;
NSError *err;
NSString *strResponse=[[NSString alloc]initWithData:responseData encoding:NSUTF8StringEncoding];
NSLog(#"response is %#",strResponse);
dit=[NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingAllowFragments error:&err];
NSArray *arrResults = [dit valueForKey:#"classifieds_mst"];
listOfObjects = [NSMutableArray array];
for(dictRes in arrResults)
{
Attributes *at = [[Attributes alloc]init];
at.classimage=[dictRes valueForKey:#"image_name"];
[listOfObjects addObject:at];
}
[tableView reloadData];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *identifier=#"cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:#"identifier"];
}
classifiedimage=[[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 300, 80)];
[cell.contentView addSubview:classifiedimage];
Attributes *att = [listOfObjects objectAtIndex:indexPath.row];
NSString *str;
str=att.classimage;
classifiedimage.image = [UIImage imageNamed:str];
return cell;
}
My requirement is i want to display images in uitableviewcells using json parser.I wrote the above code.But the images are not displayed in uitableviewcells.I want to use to display images in uitableviewcells using Asyncronous concept.Please give me any idea.I am new to the programming.Thanks in advance.
This is my json data.
{"classifieds_mst":[{"classified_id":83,image_name":"1389006378_butterfly.jpeg"},
{"classified_id":82,"image_name":"ttt.jpj"},{"classified_id":83,”image_name":"ttttt.jpj”}

Answer 1

imageNamed is used to load image from local bundle (in app).
imageWithData:dataWithURL is used to load images from url's.

Answer 2

You have to append domain name in your image name: (image_name":"1389006378_butterfly.jpeg), so that you can get URL of the image which is stored on server, now you can use below code:
[cell.yourImageView setImage:[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:yourImageNameHere]]]];

Answer 3

By referring to your JSON data, it just contain the image_name only. So first of all, you need to build the actual image url. (copy paste that actual url in browser to make sure image is available in server).
Once you have the image url, then you can use AsyncImageView instead of UIImageView in your cell. It will handle the asynchronous thing for you as you just need to set the image url only. Thats the way to go.
One more suggestion is to recheck you cellForRowAtIndexPath, as the code always creating imageView's and adding to cell each time the cell is created. That's not required when you are reusing a cell. You just need to create the image view once when cell is allocated and just assign a tag to imageview and then get the imageview based on this tag and then use it. Just for your reference, I'm posting a sample code:
if(cell == nil){
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:#"identifier"];
AsyncImageView *imgView= [[[AsyncImageView alloc]init]autorelease];
imgView.tag = 1000;
imgView.contentMode = UIViewContentModeScaleAspectFill;
[cell.contentView addSubview:imgView];
}
AsyncImageView *imgView= (AsyncImageView*)[cell.contentView viewWithTag:1000];
contactImgView.frame = CGRectMake(0, 0, 300, 80);
//imgUrl is the actual url of image that is available in datasource
[contactImgView setImageURL:imgUrl];
Hope it is clear.

Answer 4

if you are using the AFNetworking then use it to download your image like
NSArray *keys = #[#"UserID", ];
NSArray *objects = #[#(userId)];
NSDictionary *parameter = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:
[NSURL URLWithString:BaseURLString]];
[httpClient setParameterEncoding:AFJSONParameterEncoding];
[httpClient registerHTTPOperationClass:[AFJSONRequestOperation class]];
NSMutableURLRequest *request = [httpClient requestWithMethod:#"POST"
path:#"UserService.svc/GetUserInfo"
parameters:parameter];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[httpClient registerHTTPOperationClass:[AFHTTPRequestOperation class]];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
NSError* error = nil;
id jsonObject = [NSJSONSerialization JSONObjectWithData:responseObject options:NSJSONReadingAllowFragments error:&error];
}
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
dispatch_async(dispatch_get_main_queue(), ^{
[SVProgressHUD dismiss];
});
}];
[operation start];
and for image use this
[cell.userImage setImageWithURLRequest:[[NSURLRequest alloc] initWithURL:[NSURL URLWithString:userBasicInfo.imageUrl]]
placeholderImage:[UIImage imageNamed:#"facebook-no-user.png"]
success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image){
weakCell.userImage.image = image;
[weakCell setNeedsLayout];
} completion:^(BOOL success, NSError *error) {
NSLog(#"%#",[error localizedDescription]);
}];
}
failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error){
}];

Answer 5

You Create a subclass of UITableViewCell (can call it blogTableViewCell) for your cell and use that in the table.
Initialize blogTableViewCell with the JSON data (you could have an NSDictionary store the JSON info)
In blogTableViewCell create a function that loads image data on another thread (so the main thread can continue its course) and once the image is loaded, update the uiimageview on the cell to display it (This should be done on the main thread as it is a UI update)

Answer 6

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
// Configure the cell...
//cell.textLabel.text = [[resultArray objectAtIndex:indexPath.row] valueForKey:#"name"];
cell.detailTextLabel.text = [[resultArray objectAtIndex:indexPath.row] valueForKey:#"designation"];
cell.imageView.image=[UIImage imageNamed:[[resultArray objectAtIndex:indexPath.row] valueForKey:#"image"]] ;
//[cell.imageView setImageWithURL:[NSURL URLWithString:[[resultArray objectAtIndex:indexPath.row] objectForKey:#"image"]]];
// NSURL *url = [NSURL URLWithString:[resultArray objectAtIndex:indexPath .row]];
NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:[[resultArray objectAtIndex:indexPath.row] valueForKey:#"image"] ]];
cell.imageView.image = [UIImage imageWithData:imageData];
return cell;
}