在UITableViewCell中动态显示图像

Question

I have a UITableViewCell, it is scroll-disabled and with fixed sections and rows.

There are two sections, with 1 row in section 0, and several rows in section 1.

The tableView is for users to make some choices.

So, the first section (with only one row) is going to display the result of users' choices,

and no doubt the second section (with several rows) is for choosing.

Now I want to put an image in the cell of the only row of the first section,

and this image will change according to users' choose.

It is very easy to judge which png image should be displaying, but I have trouble update it.

I tried use the cell's imageView, and manually alloc a UIImageView or UIView there to display those images.

But all of them won't work, I mean they just keep what they are displaying at the beginning and never changes it, even if I set the view's background or its image to a new png.

I tried some method like

[myImage setNeedsDisplay] for the manually alloced view,

or

[thatCell setNeedsDiaplsy] & [self.tableView reloadData] for the imageView of that cell,

but in vain.

So I wonder how can I achieve this function that dynamically display an image in a UITableViewCell in different situations?

Thanks a lot!

__ _ __ update line _ ____

I'm sorry that I didn't provide my code.

and here they are.

- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath {
     static NSString *inOutTableCellIdentifier = @"DealTableViewIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:inOutTableCellIdentifier];
if (cell == nil) {
    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1
                                   reuseIdentifier:inOutTableCellIdentifier] autorelease];
    cell.textLabel.font = [UIFont fontWithName:cMyFont size:[UIFont systemFontSize]];
    cell.detailTextLabel.font = [UIFont fontWithName:cMyFont size:[UIFont smallSystemFontSize]];
     // I tried using both imageView and UIView here, but won't work

     if (indexPath.section == 0) {   
        //cell.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"moneyCell.png"]];
        cell.backgroundColor = [UIColor cyanColor];
       // cell.imageView.image = [UIImage imageNamed:@"dealDone2.png"];
        self.undoneIcon = [[[UIView alloc] initWithFrame:CGRectMake(0, 0, 50, 50)] autorelease];
        //self.undoneIcon.image = [UIImage imageNamed:@"dealUndone2.png"];
        self.undoneIcon.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"dealUndone2.png"]];
        [cell.contentView addSubview:self.undoneIcon];
        ....  // deal with other rows in section 1
        return cell;
} 
// and this is the method that update the image, the images are named "dealDoneX.png",
// where X is an integer from 0 to 4.
- (void)checkUndoneDegree {  // here I also tried 2 ways corresponding to UIView or a cell's imageView, but neither works well.
int i = 0;
if (self._date)
    i++;
if (self.moneyTextField.text)
    i++;

if (self._incomingAccount)
    i++;
if (self._expensingAccount)
    i++;
if (_dealType != kTransferView)
    if (self._type)
        i++;
NSLog(@"undone degree: %d",i);
NSString *imageName = [@"dealUndone" stringByAppendingFormat:@"%d",i];
self.undoneIcon.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:imageName]];
[self.undoneIcon setNeedsDisplay];
//    NSUInteger p[2] = {0,0};
//    UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:[NSIndexPath    indexPathWithIndexes:p length:2]];
//    [cell setNeedsDisplay];
}

and everytime I update the table's data, like changing some text of some cell,

I would call [self checkUndoneDegree] and then call [self.tableView reloadData],

But the picture is never updated, at least from the screen.

I even tried to put the codes that decide which png to set in the

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

method, but it can only make the view displaying the first png, without any updating.

Thanks for helping!

Answer 1

1. Make your undoneDegree (represented by i variable in your code) an ivar of your view controller, so it is accessible in all of it's methods, also in the UITableView delegate and data source methods.
2. Forget about setNeedsDisplay method. Since you are using UITableView to display your content, you need to play by its rules. This means you should use reloadSections:withRowAnimation: method.
3. Check again if you need self.undoneIcon . I'm pretty sure that imageView property should do. That is if you really want to display an image in the cell. If you want to create some kind of progress bar by manipulating cell's background, then use backgroundView property, or just place UIProgressView in your cell. This is what I think your want to do, after looking at your code.