"Unrecognized selector sent to instance" when using custom table cell

Question

I have implemented a custom table cell and am receiveing a runtime error ("Unrecognized selector sent to instance") when the table enters cellForRowAtIndexPath. The error occur when trying to instantiate the custom cell. I have achieved this successfully before, but now the error won't go away. I have a prtotype cell and its custom class attribute is set to the custom cell UITableViewCell subclass. Here is the custom cell:

#import "FavoriteCell.h"

@implementation FavoriteCell
@synthesize lblGaugeID, lblMainTitle, bgImage;

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    bgImage = [UIImage imageNamed:@"tableCellBG.png"];
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        UIColor *transparentBG = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];
        UIColor *foregroundColor = [UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:1.0];
        //UIColor *shadowColot = [UIColor colorWithWhite:0.75 alpha:1.0];

        CGSize size = self.contentView.frame.size;
        self.backgroundView = [[UIImageView alloc] initWithImage:bgImage];
        self.lblMainTitle = [[UILabel alloc] initWithFrame:CGRectMake(8.0, 0.5, size.width-16, size.height-40)];
        [self.lblMainTitle setFont:[UIFont systemFontOfSize:12.0]];
        [self.lblMainTitle setTextAlignment:NSTextAlignmentLeft];
        [self.lblMainTitle setAutoresizingMask:(UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight)];
        [self.lblMainTitle setBackgroundColor:transparentBG];

        self.lblGaugeID = [[UILabel alloc] initWithFrame:CGRectMake(20.0, 31.0, size.width-16, size.height-40)];
        [self.lblGaugeID setFont:[UIFont boldSystemFontOfSize:15.0]];
        [self.lblGaugeID setTextAlignment:NSTextAlignmentLeft];
        [self.lblGaugeID setTextColor:foregroundColor];
        [self.lblGaugeID setShadowOffset:CGSizeMake(0.2 , 0.2)];
        [self.lblGaugeID setAutoresizingMask:(UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight)];
        [self.lblGaugeID setBackgroundColor:transparentBG];

        [self.contentView addSubview:lblGaugeID];
        [self.contentView addSubview:lblMainTitle];
    }
    return self;
}

@end

and here is where it is instatiated (excerpted from my view controller class):

-(FavoriteCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString *cellIdentifier = @"favoriteCell";
    FavoriteCell *cell = (FavoriteCell*)[tableView dequeueReusableCellWithIdentifier:cellIdentifier]; //error
    if(cell == nil){
        cell = [[FavoriteCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
    }
    NSString *siteName = [faveKeys objectAtIndex:indexPath.row];

    [cell.lblMainTitle setText:siteName];
    [cell.lblGaugeID setText:[allFavorites objectForKey:siteName]];
    return cell;
}

Here is the full error message:

* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFConstantString instantiateWithOwner:options:]: unrecognized selector sent to instance 0x24bb0'

Can anyone offer some advice on what to check? Thanks! Vivian

Answer 1

Using - (void)registerNib:(UINib *)nib forCellReuseIdentifier:(NSString *)identifier was a good idea if you had defined your custom cell in a separate NIB file. The problem was that you passed an NSString rather than a UINib object.

Do this instead:

[self.tblFavorites registerNib:[UINib nibWithNibName:@"favoriteCellView" bundle:nil] forCellReuseIdentifier:@"favoriteCell"];

However since you used a prototype cell rather than a separate NIB, there's no need to do this at all. Instead you just need to make sure the prototype cell's reuse identifier is set properly (in this case to "favoriteCell").