Add different images to UIImageView of cells in UITableView - objective-c

Question

Needless to say, i am a novice. I am trying to add images and text to a UITableView. I have been able to add the text but I am having problems with adding different images to the desired text.
I have 2 separate PHP codes for 1 database:
The first gets the text and an id for the image assigned to the text (imageID)
The second uses the id (from the first PHP) to acquire the image
My code is fine but currently only 1 image is appearing for all the text
My question is how do I assign each image to their text ?
And how do I not assign an image to the text that do not have images as some of the texts don't have images with them?
My code is as follows:
Connection and data download:
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// Create an array to store the locations
NSMutableArray *list = [[NSMutableArray alloc] init];
// Parse the JSON that came in
NSError *error;
jsonArray = [NSJSONSerialization JSONObjectWithData:downloadedData options:NSJSONReadingAllowFragments error:&error];
// Loop through Json objects, create question objects and add them to our questions array
for (int i = 0; i < jsonArray.count; i++)
{
jsonElement = jsonArray[i];
// Create a new cell object and set its props to JsonElement properties
if (![jsonElement [#"Thought"] isEqual:[NSNull null]])
{
NSString *listText =jsonElement [#"Thought"];
if ([listText length] > 0)
{
NSString *cellText = jsonElement[#"Thought"];
[list addObject:cellText];
NSLog(#"list Cell: %#", cellText);
}
if (![jsonElement [#"filename"] isEqual:[NSNull null]])
{
imageID = jsonElement[#"id"];
}
NSLog(#"Cell Image: %#", imageID);
}
}
[[self tableView1] reloadData];
}
Cells in the table:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *simpleIdentifier = #"SimpleIdentifier";
cell = [tableView dequeueReusableCellWithIdentifier:simpleIdentifier];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:simpleIdentifier];
}
cell.textLabel.text = [list objectAtIndex:indexPath.row];
cell.textLabel.font = [UIFont italicSystemFontOfSize:20];
if ([imageID length] > 0)
{
urlStr = [NSString stringWithFormat:#"http://database.name/getimage.php?id=%#", imageID];
NSURL *imageUrl = [NSURL URLWithString:urlStr];
NSData *imageData = [NSData dataWithContentsOfURL:imageUrl];
UIImage *imageLoad = [[UIImage alloc] initWithData:imageData];
cell.imageView.image = imageLoad;
}
return cell;
}

Answer 1

You should not leave any case untouched in tableview:cellForRowAtIndexPath. What happens when you try this
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *simpleIdentifier = #"SimpleIdentifier";
cell = [tableView dequeueReusableCellWithIdentifier:simpleIdentifier];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:simpleIdentifier];
}
cell.textLabel.text = [list objectAtIndex:indexPath.row];
cell.textLabel.font = [UIFont italicSystemFontOfSize:20];
if ([imageID length] > 0)
{
urlStr = [NSString stringWithFormat:#"http://database.name/getimage.php?id=%#", imageID];
NSURL *imageUrl = [NSURL URLWithString:urlStr];
NSData *imageData = [NSData dataWithContentsOfURL:imageUrl];
UIImage *imageLoad = [[UIImage alloc] initWithData:imageData];
cell.imageView.image = imageLoad;
}
else //I assume this is the case when a row does not contain an image right?
{
cell.imageView.image = nil; //Or the below line for better aestethics
//cell.imageView.image = [UIImage imageNamed:#"placeholderimage.png"];
}
return cell;
}
By the way NSData *imageData = [NSData dataWithContentsOfURL:imageUrl]; is called everytime tableview:cellForRowAtIndexPath is triggered and this happens alot. As far as I know dataWithContentsOfURL: is a heavy process and stalls the UI until it downloads the image. So it would be better to download one specific image once and save it in a NSMutableArray or NSMutableDictionary. For instance:
//in your .m
#interface ViewController ()
#property NSMutableDictionary * imageIdDictionary;
#end
#implementation ViewController
-(void)viewDidLoad
{
[super viewDidLoad];
imageIdDictionary = [[NSMutableDictionary alloc] init];
}
And change your tableView:cellForRowAtIndexPath: to:
//Added this. You need a second array just like `list` which has all the different imageID's stored
imageID = [list2 objectAtIndex:indexPath.row];
if ([imageID length] > 0) {
if([self.imageIdDictionary objectForKey:imageID]) {
cell.imageView.image = [self.imageIdDictionary objectForKey:imageID];
}
else {
urlStr = [NSString stringWithFormat:#"http://database.name/getimage.php?id=%#", imageID];
NSURL *imageUrl = [NSURL URLWithString:urlStr];
NSData *imageData = [NSData dataWithContentsOfURL:imageUrl];
UIImage *imageLoad = [[UIImage alloc] initWithData:imageData];
cell.imageView.image = imageLoad;
[self.imageIdDictionary setValue:imageLoad forKey:imageID];
//added these two lines!!!!!!!
NSArray * array = [NSArray arrayWithObject:[NSIndexPath indexPathForRow:indexPath.row inSection:indexPath.section]];
[table reloadRowsAtIndexPaths:array withRowAnimation:UITableViewRowAnimationFade];
}
}
else {
cell.imageView.image = nil; //Or the below line for better aestethics
//cell.imageView.image = [UIImage imageNamed:#"placeholderimage.png"];
}
This will make your application run much smoother

Answer 2

UITableView's cells are reusable. It means that the cells which are not visible will show the same content before you reset.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *simpleIdentifier = #"SimpleIdentifier";
cell = [tableView dequeueReusableCellWithIdentifier:simpleIdentifier];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:simpleIdentifier];
}
cell.textLabel.text = #"";
cell.imageView.image = nil;
cell.textLabel.text = [list objectAtIndex:indexPath.row];
cell.textLabel.font = [UIFont italicSystemFontOfSize:20];
...
}
Just add the reset codes.