Custom UITableViewCell redraw issues

Question

I have a custom UITableView cell that I've added a textbox to for editing, that shows and hides based on the edit mode. I've also tried adding a vertical line that shows when editing, and it does that, but I'm running into some drawing issues. I just added a green checkmark rightView to start working on input validation feedback, and I'm seeing similar issues.

Here is the code for the cell, and part of my cellForRowAtIndexPath.

#import <UIKit/UIKit.h>

    @interface EditableCellStyle2 : UITableViewCell {
        CGRect editRect;
        UITextField *editField;
        UIView *lineView;
    }

    @property (nonatomic, readonly, retain) UITextField *editField;
    @property (nonatomic, readonly, retain) UIView *lineView;

    @end

---

#import "EditableCellStyle2.h"


@implementation EditableCellStyle2

@synthesize editField;
@synthesize lineView;


- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {

    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        // Initialization code.
        editRect = CGRectMake(83, 12, self.contentView.bounds.size.width-83, 19);

        editField = [[UITextField alloc] initWithFrame:editRect];
        editField.font = [UIFont boldSystemFontOfSize:15];
        editField.textAlignment = UITextAlignmentLeft;
        editField.textColor = [UIColor blackColor];
        editField.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleHeight;

        [self.contentView addSubview:editField];

        self.editField.enabled = NO;
        self.editField.hidden = YES;


        lineView = [[UIView alloc] initWithFrame:CGRectMake(80, 0, 1, self.contentView.bounds.size.height)];
        self.lineView.backgroundColor = [UIColor lightGrayColor];
        [self.contentView addSubview:lineView];
        self.lineView.hidden = YES;
    }
    return self;
}

- (void)setSelected:(BOOL)selected animated:(BOOL)animated {

    [super setSelected:selected animated:animated];

    // Configure the view for the selected state.
}

-(void)layoutSubviews
{
    [super layoutSubviews]; // layouts the cell as UITableViewCellStyleValue2 would normally look like

    editRect = CGRectMake(83, 12, self.contentView.frame.size.width-self.detailTextLabel.frame.origin.x-10, 19);
    editField.frame = editRect;
}


- (void)willTransitionToState:(UITableViewCellStateMask)state {
    [super willTransitionToState:state];

    if (state & UITableViewCellStateEditingMask) {
        self.detailTextLabel.hidden = YES;
        self.editField.enabled = YES;
        self.lineView.hidden = NO;
        self.editField.hidden = NO;
    }
}

- (void)didTransitionToState:(UITableViewCellStateMask)state {
    [super didTransitionToState:state];

    if (!(state & UITableViewCellStateEditingMask)) {
        self.editField.enabled = NO;
        self.editField.hidden = YES;
        self.lineView.hidden = YES;
        self.detailTextLabel.hidden = NO;
        self.editField.text = self.detailTextLabel.text;
    }
}


- (void)dealloc {
    [editField release];
    [lineView release];

    [super dealloc];
}


@end

---

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

    // handling every section by hand since this view is essentially static. Sections 0, 1, 2, and 4 use a generic editable cell.
    // Section 3 uses the multiline address cell.

    static NSString *CellIdentifier = @"Cell";

    EditableCellStyle2 *cell = (EditableCellStyle2 *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (indexPath.section == 0 || indexPath.section == 1 || indexPath.section == 2 || indexPath.section == 4) {
        if (cell == nil) {
            cell = [[[EditableCellStyle2 alloc] initWithStyle:UITableViewCellStyleValue2 reuseIdentifier:CellIdentifier] autorelease];
        }
    }

    // Configure the Odometer
    if (indexPath.section == 0) {
        NSArray *array = [sectionsArray objectAtIndex:indexPath.section];
        NSDictionary *dictionary = [array objectAtIndex:indexPath.row];

        cell.textLabel.text = @"Odometer";
        cell.detailTextLabel.text = [NSString stringWithFormat:@"%@", [dictionary objectForKey:@"Odometer"]];
        cell.tag = kOdometer;
        cell.editField.text = cell.detailTextLabel.text;
        cell.editField.placeholder = @"Odometer";
        cell.editField.tag = kOdometer;
        cell.editField.keyboardType = UIKeyboardTypeNumberPad;

        // Create a view for the green checkmark for odometer input validation and set it as the right view.
        UIImage *checkImage = [UIImage imageNamed:@"tick.png"];
        UIImageView *checkImageView = [[[UIImageView alloc] initWithImage:checkImage] autorelease];
        cell.editField.rightView = checkImageView;
        cell.editField.rightViewMode = UITextFieldViewModeAlways;
    }

return cell;
}

---

There is more to it but all the cells are built the same way.

The problems are that, when in edit mode, the vertical lines will display properly. When I leave edit mode, any cells that were off screen when I go to normal mode still have the vertical line (it doesn't get hidden). Also, now that I've added the imageView for the checkmark indicator, any cells that are off screen when switching modes gain the checkmark. (only section 0 sets it up).

I've also noticed that if i do cell.setNeedsDisplay, the text label and detail text label won't update if the data source has been updated. I have to do [self.tableView reloadData] which skips any active animations.

I'm sure these issues are related to me using a custom cell + dequeueReusableCellWithIdentifier, but I can't find exactly what.

Any feedback or a push in the right direction would be appreciated.

Edit: Not using reusable cells seems to have resolved the above issues. I'm still open to feedback on the cell code. I forgot one other issue that may or may not be related. One of my cells has a "tap to view list" button. If I enter data into the cells while in edit mode, then hit that button to choose some info from a list (it displays a modal table view), when I dismiss the modal view, all of the cells' edited data has reverted to their original state. I'm not calling reload data when I dismiss the modal view controller. I thought this might be fixed by not using reusable cells but it isn't.

Answer 1

You need to prepare the cell for reuse. Try adding this to the EditableCellStyle2 implementation:

- (void)prepareForReuse {
    [super prepareForReuse];
    [self didTransitionToState:UITableViewCellStateDefaultMask];
}

Answer 2

Maybe you trimmed too much for your post, but in the posted code your reusable cell handling is all wrong.

First of all, each different type of cell needs its own CellIdentifier. In your case (judging from your code comment), that means at least a different identifier for section 3 versus sections 0, 1, 2, and 4. You may also want to do a separate identifier for section 0, so you don't have to keep removing and readding that checkmark. The different identifier needs to be used for both the dequeueReusableCellWithIdentifier: and initWithStyle:reuseIdentifier:` for the appropriate sections.

The second problem is that you are not resetting the cells correctly. There are two "kinds" of initialization that must be done to a UITableViewCell: initialization that is the same for every cell of its type, and initialization that depends on the specific row being displayed. The first kind can (and should) only be done once, when a new cell is allocated. The second kind must be done every time through tableView:cellForRowAtIndexPath:. You seem to be doing the first correctly for your EditableTableCell2 class in its init method, but I see nowhere in there where you do the per-row initialization: you never reset selected, or the cell state, or the contents of the edit field, or remove the checkImageView since you are using the same kind of cell for section 0 versus the other sections. If you want, the reset selected, state, and clearing out the checkbox image and field contents can be done in prepareForReuse on your EditableTableCell2 class.

The third problem, which is almost certainly due to over-trimming, is that you never create this "multiline address" cell for section 3. You'll end up maybe reusing a random EditableTableCell2, or maybe crashing on an exception from the framework when you return nil from tableView:cellForRowAtIndexPath:.