Why does my tableview break at the 4th entry? - iphone

Question

This is the code I have. It works fine for the first 3 entries, then on the 4th entry, it starts showing the same cell content as other cells, despite the height of each cell being correct. Can anybody spot any problems that i'm not seeing here? The cell.textLabel.text is there purely for testing purposes, and comes back as the correct cell number, even if the contents of the cell aren't right. Since it's set at the same time as the content, this leads me to believe the problem is not in cellForRowAtIndexPath.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
JCell *cell = (JCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
UIImageView *imageView;
if (cell == nil) {
cell = [[JCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
imageView = [[UIImageView alloc] init];
imageView.contentMode = UIViewContentModeCenter;
[cell addSubview:imageView];
}
UIImage *image = [self.mediaDelegate largeThumbnailForMediaAtIndex:indexPath.row];
imageView.frame = CGRectMake(0, IMAGE_SPACING, image.size.width, image.size.height);
imageView.image = image;
imageView.center = CGPointMake(cell.bounds.size.width / 2, imageView.center.y);
cell.textLabel.text = [NSString stringWithFormat:#"%i", indexPath.row];
return cell;
}
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
int mediaHeight = [self.mediaDelegate heightForLargeThumbnailForMediaAtIndex:indexPath.row];
return mediaHeight + (IMAGE_SPACING * 2);
}
It's always going to be a JImage, because i haven't started on movie support yet.
-(UIImage *)largeThumbnailForMediaAtIndex:(int)index
{
id media = [self.media objectAtIndex:index];
if ([media isKindOfClass:[JImage class]]) {
JImage *image = media;
return [image getLargeThumbnail];
}
else if ([media isKindOfClass:[JMovie class]]) {
JMovie *movie = media;
return [movie getLargeThumbnail];
}
else {
return nil;
}
}
-(UIImage *)getLargeThumbnail {
if (self.largeThumbnail == nil) {
UIImage *originalImage = [UIImage imageWithContentsOfFile:self.originalImage];
UIImage *resizedImage = [originalImage imageScaledToFitSize:LARGE_THUMBNAIL_SIZE];
self.largeThumbnail = #"Generating";
dispatch_queue_t myQueue = dispatch_queue_create("LargeThumbnailQueue", 0);
dispatch_async(myQueue, ^{
NSString *filePath = [JImage writeImageToFile:resizedImage];
self.largeThumbnail = filePath;
});
return resizedImage;
}
else if ([_largeThumbnail isEqualToString:#"Generating"]) {
UIImage *originalImage = [UIImage imageWithContentsOfFile:self.originalImage];
UIImage *resizedImage = [originalImage imageScaledToFitSize:LARGE_THUMBNAIL_SIZE];
return resizedImage;
}
else {
NSString *filePath = self.largeThumbnail;
UIImage *image = [UIImage imageWithContentsOfFile:filePath];
return image;
}
}
+(NSString *)writeImageToFile:(UIImage *)image {
NSData *fullImageData = UIImageJPEGRepresentation(image, 1.0);
NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:#"Documents/Images/"];
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOL isDirectory = NO;
BOOL directoryExists = [fileManager fileExistsAtPath:path isDirectory:&isDirectory];
if (directoryExists) {
} else {
[fileManager createDirectoryAtPath:path withIntermediateDirectories:NO attributes:nil error:nil];
}
NSString *retinaSupport;
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)] && [[UIScreen mainScreen] scale] == 2){
retinaSupport = #"#2x";
}
NSString *name = [NSString stringWithFormat:#"%#%#.jpg", [JMedia generateUuidString], retinaSupport];
NSString *filePath = [path stringByAppendingPathComponent:name];
[fullImageData writeToFile:filePath atomically:YES];
return filePath;
}
Any assistance or help with this problem is greatly appreciated.

Answer 1

when you reuse a cell (ie. you don't enter if (cell == nil) you don't have an imageView. imageView will be nil.
Add a tag to retrieve that imageView when you reuse your cells:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
JCell *cell = (JCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
UIImageView *imageView;
if (cell == nil) {
cell = [[JCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
imageView = [[UIImageView alloc] init];
imageView.contentMode = UIViewContentModeCenter;
imageView.tag = 1234;
[cell addSubview:imageView];
}
imageView = [cell viewWithTag:1234];
UIImage *image = [self.mediaDelegate largeThumbnailForMediaAtIndex:indexPath.row];
imageView.frame = CGRectMake(0, IMAGE_SPACING, image.size.width, image.size.height);
imageView.image = image;
imageView.center = CGPointMake(cell.bounds.size.width / 2, imageView.center.y);
cell.textLabel.text = [NSString stringWithFormat:#"%i", indexPath.row];
return cell;
}

Answer 2

Shouldn't you rather do
UIImage *image = [self.mediaDelegate largeThumbnailForMediaAtIndex:indexPath.row];
cell.imageView.frame = CGRectMake(0, IMAGE_SPACING, image.size.width, image.size.height);
cell.imageView.image = image;
cell.imageView.center = CGPointMake(cell.bounds.size.width / 2, imageView.center.y);
?
(or at least, you should retrieve the imageView from the cell and not use what it looks to be a instance variable)

Answer 3

You're only allocating imageView to the cell if it goes into the
if (cell == nil)
block. So after the tableview has created a couple of instances, it will reuse them and you won't get an imageView added to it.
EDIT:
UIImageView *imageView; <------------ imageView is nil
if (cell == nil) {
cell = [[JCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
imageView = [[UIImageView alloc] init];
imageView.contentMode = UIViewContentModeCenter;
[cell addSubview:imageView];
}
UIImage *image = [self.mediaDelegate largeThumbnailForMediaAtIndex:indexPath.row];
// At this point, imageView is still nil - not been initialised to anything
imageView.frame = CGRectMake(0, IMAGE_SPACING, image.size.width, image.size.height);
imageView.image = image;
imageView.center = CGPointMake(cell.bounds.size.width / 2, imageView.center.y);