CODEWITHSUNDEEP
iosobjective-cuicollectionviewuicollectionviewcell
Steaphann
Steaphann

Reputation: 2777

every 4 block another background color in a uicollectionView

I have a collectionView with a list of cells. Each cell has a backgroundColor. So it should be like this.

At the moment I'm doing it like this. I've declared a private int in my ViewController and in my cellForItemAtIndexPath I do this. 

- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    //  MagazineCollectionViewCell *cell = (MagazineCollectionViewCell *)[cv dequeueReusableCellWithReuseIdentifier:@"MagazineCollectionViewCell " forIndexPath:indexPath];
    ReisCategorieCell *cell = [cv dequeueReusableCellWithReuseIdentifier:@"ReisCategorieCell" forIndexPath:indexPath];
    cell.delegationListener = self;

    Reiscategorie *category = [arrCategories objectAtIndex:indexPath.row];

    cell.reisCategorie = category;

    cell.lblTitle.font = [UIFont fontWithName:@"Dosis-Medium" size:35];
    cell.lblDescription.font = [UIFont fontWithName:@"Dosis-Medium" size:15];
    [cell.btnAanbod.titleLabel setFont:[UIFont fontWithName:@"Dosis-Medium" size:23]];

    cell.lblTitle.textColor = [UIColor whiteColor];
    cell.lblDescription.textColor = [UIColor whiteColor];
    [cell.btnAanbod.titleLabel setTextColor:[UIColor whiteColor]];
    cell.btnAanbod.titleLabel.textColor = [UIColor whiteColor];

    countBackground++;
    if(countBackground>4){
        countBackground = 0;
    }
    if (countBackground == 1) {
        cell.contentView.backgroundColor = [UIColor aslRed];
        cell.btnAanbod.backgroundColor = [UIColor aslBrown];
    }else if (countBackground == 2){
        cell.contentView.backgroundColor = [UIColor aslBrown];
        cell.btnAanbod.backgroundColor = [UIColor aslGray2];
    }else if (countBackground == 3){
        cell.contentView.backgroundColor = [UIColor aslGray];
        cell.btnAanbod.backgroundColor = [UIColor aslBrown];
    }else if (countBackground == 4){
        cell.contentView.backgroundColor = [UIColor aslGray2];
        cell.btnAanbod.backgroundColor = [UIColor aslBrown];
    }

    if([category.cat_name isEqualToString:@"Lapland"]){
        cell.btnLapland.hidden = NO;
    }else{
        cell.btnLapland.hidden = YES;
    }
    [cell.btnAanbod setTitle:NSLocalizedString(@"btnAanbod", nil) forState:UIControlStateNormal];
    cell.lblTitle.text = category.cat_name;
    cell.lblDescription.text = category.cat_description;
    return cell;
}

This works if you scroll slowly. But if you are scrolling to fast the colors are getting mixed up. So can anybody help me with this?

Upvotes: 0

Views: 231

Answers (2)

Maximilian Liesegang
Maximilian Liesegang

Reputation: 994

The problem is:

if(countBackground>4){
    countBackground = 0;
}

You set countBackground to 0 and don't increment in the cell after that. A soulution would be to use countBackground = 1

A better solution would be using the Modulo operation. Use:

countBackground = indexPath.row % 4
if (countBackground == 0) {
    //you are in row 0, 4, 8, ... -> Red color
} else if (countBackground == 1) {
    //you are in row 1, 5, 9, ... -> Green color
} else if (countBackground == 2) {
    //you are in row 2, 6, 10, ... -> Orange color
} else if (countBackground == 3) {
    //you are in row 3, 7, 11, ... -> Yellow color
}

Upvotes: 0

Rinat Khanov
Rinat Khanov

Reputation: 1576

You need to rely on indexPath.row instead of using manual cell counting. It doesn't work because your cells get reused while you scroll your UICollectionView.

Assuming that you have one section in your UICollectionView, you may use something like this to determine color for each cell: 

switch (indexPath.row % 4) {
        case 0:
            // yellow
            break;
        case 1:
            // orange
            break;
        case 2:
            // green
            break;
        case 3:
            // red
            break;
    }

I haven't tested this logic, but this general approach should work.

Upvotes: 1

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