How to change color of selected row in UIPickerView

Question

Ok, maybe I'm missing something really simple and I apologize if that's the case, however, I've googled every permutation of the title and have not found! So this is simply what I want to do: change the background color of the label I'm using as the row view in a 2 component pickerview when that row has been selected. So I thought this would work:

if (row == [pickerview selectedRowForComponent])
    viewlabel.backgroundColor = redcolor;

but this doesn't work. It seems to arbitrarily choose which row to color and sometimes even give a bad access error. I've tried all different clauses to no effect! ANy suggestions would be greatly appreciated!!

Here's the full method:

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{

    if (component == kNumberComponent) {


#define PICKER_LABEL_FONT_SIZE 24
#define PICKER_LABEL_ALPHA 1.0
        // UIFont *font = [UIFont boldSystemFontOfSize:PICKER_LABEL_FONT_SIZE];
        UIFont *font = [ UIFont fontWithName:@"AppleGothic"  size:24];
        UILabel *carsLabel =[ [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 75, 50) ]autorelease];
        //[picker selectRow:row inComponent:component animated:YES];
        NSString *pickerText = [self.numbers objectAtIndex:(int)row];
        carsLabel.text = pickerText;
        carsLabel.textAlignment = UITextAlignmentCenter;
        NSLog(@"carsLabel = %@",carsLabel.text);
        //carsLabel.text = @"maybe because the string isn't long enough";
        carsLabel.textColor = [UIColor blackColor];
        carsLabel.font = font;





        carsLabel.opaque = YES;


        [view addSubview:carsLabel];

        return carsLabel;   
    } else {
        UIFont *font = [ UIFont fontWithName:@"AppleGothic"  size:18];

        UILabel *carsLabel = [[[UILabel alloc] initWithFrame:CGRectMake(0, 0, 225, 50)] autorelease];
        id fact = [self.facts objectAtIndex:(int)row];
        NSString *pickerText = @"Dictionary Entry";
        if ( [fact isKindOfClass:[NSString class]]) {


            pickerText = [self.facts objectAtIndex:(int)row];

        } 
        carsLabel.text = pickerText;
        carsLabel.textAlignment = UITextAlignmentCenter;
        NSLog(@"carsLabel = %@",carsLabel.text);
        //carsLabel.text = @"maybe because the string isn't long enough";
        carsLabel.textColor = [UIColor blackColor];
        carsLabel.font = font;
        if ( row == 0) {
        carsLabel.backgroundColor = [UIColor redColor];

        }
        //carsLabel.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"blackboard.png"]];;
        carsLabel.opaque = YES;

        [view addSubview:carsLabel];

        return carsLabel;
    }


    return nil;
}

Answer 1

Normally, I use this method:

I use the custom view for show the row item

-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {      UILabel *label = (id)view;      if (!label)     {          label= [[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, [pickerView rowSizeForComponent:component].width, [pickerView rowSizeForComponent:component].height)];         label.textAlignment = NSTextAlignmentCenter;         label.textColor = [UIColor whiteColor];         label.text = _arrayStringPicker[row];      }        return label; 

I change color of row selected with:

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {      UILabel *labelSelected = (UILabel*)[pickerView viewForRow:row forComponent:component];     [labelSelected setTextColor:[UIColor redColor]];  } 

Answer 2

Swift implementation

extension PickerViewController: UIPickerViewDelegate {
    func pickerView(pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
        var color: UIColor!
        if pickerView.selectedRowInComponent(component) == row {
            color = UIColor.redColor()
        } else {
            color = UIColor.blackColor()
        }

        let attributes: [String: AnyObject] = [
            NSForegroundColorAttributeName: color,
            NSFontAttributeName: UIFont.systemFontOfSize(15)
        ]

        return NSAttributedString(string: rows[row], attributes: attributes)
    }

    func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        //this will trigger attributedTitleForRow-method to be called
        pickerView.reloadAllComponents()
    }
}

Answer 3

The correct format for viewForPicker is:

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{
    UILabel *label = (UILabel*) view;
    if (label == nil)
    {
        label = [[UILabel alloc] init];
    }

    [label setText:@"Whatever"];

    // This part just colorizes everything, since you asked about that.

    [label setTextColor:[UIColor whiteColor]];
    [label setBackgroundColor:[UIColor blackColor]];
    CGSize rowSize = [pickerView rowSizeForComponent:component];
    CGRect labelRect = CGRectMake (0, 0, rowSize.width, rowSize.height);
    [label setFrame:labelRect];

    return label;
}

The problem with the code above is: it colorizes the labels, but not the picker, itself. So, when you roll to one end or the other, there's a blank spot where you can see the white background. Setting [myPicker setBackgroundColor...] doesn't do what one might hope.