UITableView with Custom Cell and Separator. Alpha value changes on scroll - ios

Question

I have a UITableView with a Custom Cell. Some custom cells are being loaded with an image.
And I'm adding a custom separator for the cells that have an image. The problem arises on scrolling. Whenever I scroll, the UIView opacity changes.
Here is my code :
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
CustomCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell == nil){
NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:#"CustomCell" owner:self options:nil];
cell = [topLevelObjects objectAtIndex:0];
}
if (cell && (NSNull*) imageString != [NSNull null])
{
UIView* separatorLineView; = [[UIView alloc] initWithFrame:CGRectMake(0, -1, 320, 5)];
separatorLineView.backgroundColor = [UIColor blackColor];
separatorLineView.alpha = 0.2;
[cell.contentView addSubview:separatorLineView];
}
Alpha for the view given is 0.2 and on scrolling it becomes thicker and thicker. How can I solve this issue?

Answer 1

Do what #rmaddy and #rdelmar have suggested but since you're using a custom cell anyways, the quickest way, imho, would be:
Add this line to the cell's contentView via the Interface Builder directly
#property (strong, nonatomic) IBOutlet UIView *vwLine;
also #synthesize vwLine;
Set it's frame, background color & alpha value (obviously)
Set it's hidden property to YES
When you do the imageString != [NSNull null] check
if TRUE then [cell.vwLine setHidden:NO];
Example:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
CustomCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell == nil) {
NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:#"CustomCell"
owner:self
options:nil];
cell = [topLevelObjects objectAtIndex:0];
}
if (imageString != [NSNull null]) {
[cell.vwLine setHidden:NO];
}
}

Answer 2

I think the problem is that you're adding a separatorLineView to cells that already have one as you scroll, so what you're seeing is lines on top of other lines. You could fix that by adding a tag to your line view, and checking if the cell has a subview with that tag, and if so, don't add another line.

Answer 3

In your code might be problem of reusability of cell. So try with following code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
.
.
.
.
if(cell == nil)
{
NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:#"CustomCell" owner:self options:nil];
cell = [topLevelObjects objectAtIndex:0];
if(cellHasImage == YES)
{
//// just initialize UIView and add as addSubview of cell.contentView
UIView* separatorLineView; = [[UIView alloc] init];
separatorLineView.frame = CGRectMake(0, -1, 320, 5);
separatorLineView.tag = 111; // set whatever you like
[cell.contentView addSubview:separatorLineView];
}
}
.
.
.
/// get UIView base on it's tag
if(cellHasImage == YES)
{
UIView* separatorLineView; = (UIView *) [cell.contentView viewWithTag:111];
separatorLineView.backgroundColor = [UIColor blackColor];
separatorLineView.alpha = 0.2;
}
.
.
.
return cell;
}