Problem with CAGradientLayer in a custom UIView within a UITableViewCell

Question

I have a somewhat special situation that I need help with. I have a CustomView which I am placing in every UITableViewCell in my UITableView. No problems there.

Within my CustomView is a UILabel which displays some text given to it. Depending on the length of the text, the width of the CustomView grows/shrinks. All fine.

The problem I am having is with a sublayer in my CustomView which is a gradient (CAGradientLayer). The gradient size will not grow/shrink off screen on cells not in view.

Let me show you some code... I create my CustomView like so:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

static NSString *CellIdentifier = @"Cell";

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];

    CustomView *custom = [[CustomView alloc] init];
    custom.tag = 777;
    [cell.contentView addSubview:custom];
    [custom release];

}

}

I don't initWithFrame at this stage as the cell could get reused and the width is always wrong. Once the cell is there, I call a method configureCell: where I do the following:

CGSize teamMaxSize = CGSizeMake(300, 18);
CGSize teamNewSize = [[managedObject valueForKey:@"category"] 
    sizeWithFont:[UIFont systemFontOfSize:kFontSizeTeam]
    constrainedToSize:teamMaxSize
    lineBreakMode:UILineBreakModeWordWrap];

CustomView *lozenge = (CustomView *) [cell.contentView viewWithTag:777];
lozenge.frame = CGRectMake(10, 5, teamNewSize.width+12, 18);
[lozenge resetSize];
[lozenge setLabel:[managedObject valueForKey:@"category"]];

This works fine, the width of my CustomView is setup as per the length of the 'category' key. The resetSize; method above simply resizes the UILabel I mentioned before to the new frame of the CustomView before I fill it with the value.

Anyway, back to my issue. I am creating the background gradient in the drawRect: method of my CustomView. It works fine, however is the size of the CustomView at init. After I resize I need to resize the gradient.frame. So, I tried adding

gradient.frame = self.bounds

When I call resetSize in my aforementioned code. However when scrolling through the UITableView I can see the gradient literally filling from left to right as it loads into view. Is there anyway I can get this to happen 'off screen' so the CustomView is filled with the gradient as soon as it appears?

bosmacs bosmacs · Accepted Answer · 2010-09-17T20:33:21

Instead of creating a gradient in drawRect:, have you considered using CAGradientLayer as the layer class of your custom view, e.g.:

+ (Class)layerClass
{
    return [CAGradientLayer class];
}

Then you can perform any setup of your gradient in your initializer, via self.layer.

Problem with CAGradientLayer in a custom UIView within a UITableViewCell

1 Answers