objective-c - 自定义单元格中具有备用背景颜色的 UITableViewCell

Question

我希望我的 UITableViewCells 的背景每显示两个单元格就具有不同的颜色，但是当我向下和向后滚动时，它们都具有相同的颜色。知道我的单元格具有不同的 contentView 大小(根据它们的内容)，我如何才能获得这种效果？

#define FONT_SIZE 14.0f
#define CELL_CONTENT_WIDTH 320.0f
#define CELL_CONTENT_MARGIN 20.0f
#define NAME_CELL_HEIGHT 20.0f

#import "CartCell.h"

@implementation CartCell

@synthesize nameLabel = _nameLabel;
@synthesize ingredientsLabel = _ingredientsLabel;
@synthesize myStore;

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

    myStore = [Store sharedStore];

    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {

        self.nameLabel = nil;
        self.ingredientsLabel = nil;

        // SET "NAME" CELL
        self.nameLabel = [[UILabel alloc] initWithFrame:CGRectZero];
        [self.nameLabel setLineBreakMode:UILineBreakModeWordWrap];
        [self.nameLabel setMinimumFontSize:FONT_SIZE];
        [self.nameLabel setNumberOfLines:1];
        [self.nameLabel setTag:1];
        self.nameLabel.font = [UIFont fontWithName:@"Helvetica-Bold" size:18];
        [self.nameLabel sizeToFit];
        self.nameLabel.backgroundColor = [UIColor clearColor];
        [[self contentView] addSubview:self.nameLabel];

        // SET "INGREDIENTS" CELL
        self.ingredientsLabel = [[UILabel alloc] initWithFrame:CGRectZero];
        [self.ingredientsLabel setLineBreakMode:UILineBreakModeWordWrap];
        [self.ingredientsLabel setMinimumFontSize:FONT_SIZE];
        [self.ingredientsLabel setNumberOfLines:0];
        [self.ingredientsLabel setFont:[UIFont systemFontOfSize:FONT_SIZE]];
        [self.ingredientsLabel setTag:2];
        self.ingredientsLabel.backgroundColor = [UIColor clearColor];
        [[self contentView] addSubview:self.ingredientsLabel];

        if (myStore.cellBackgroundShouldBeLight == YES) {
            NSLog(@"clear [in] ? %@", myStore.cellBackgroundShouldBeLight ? @"Yes" : @"No");
            self.contentView.backgroundColor = [[UIColor alloc]initWithRed:87.0/255.0 green:168.0/255.0 blue:229.0/255.0 alpha:1];
            myStore.cellBackgroundShouldBeLight = NO;
        } else {
            NSLog(@"clear [in] ? %@", myStore.cellBackgroundShouldBeLight ? @"Yes" : @"No");
            self.contentView.backgroundColor = [[UIColor alloc]initWithRed:187.0/255.0 green:268.0/255.0 blue:229.0/255.0 alpha:1];
            myStore.cellBackgroundShouldBeLight = YES;
        }

    }

    return self;
}


- (void)setSelected:(BOOL)selected animated:(BOOL)animated
{
    [super setSelected:selected animated:animated];

    // Configure the view for the selected state
}

@end

更新:

我知道尝试按照建议在 cellForRowAtIndexPath 中设置它，但我得到了相同的结果:第一次向下滚动时工作正常，但再次向上滚动时弄乱了单元格背景颜色。

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

    static NSString *CellIdentifier = @"CartCell";
    CartCell *cell = (CartCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    Recipes *info = [_fetchedResultsController objectAtIndexPath:indexPath];

    if (cell == nil) 
    {
        cell = [[CartCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];

    }

//    if (!cell.nameLabel) {
//        cell.nameLabel = (UILabel*)[cell viewWithTag:1];
//        //        cell.nameLabel = (UILabel*)[cell viewWithTag:1];
//    }
//    if (!cell.ingredientsLabel)
//        cell.ingredientsLabel = (UILabel*)[cell viewWithTag:2];

    CGSize constraint = CGSizeMake(CELL_CONTENT_WIDTH - (CELL_CONTENT_MARGIN * 2), 20000.0f);
    CGSize size = [info.ingredients sizeWithFont:[UIFont systemFontOfSize:FONT_SIZE] constrainedToSize:constraint lineBreakMode:UILineBreakModeWordWrap];

    [cell.nameLabel setFrame:CGRectMake(10, 10, CELL_CONTENT_WIDTH - (CELL_CONTENT_MARGIN * 2), NAME_CELL_HEIGHT)];
    [cell.ingredientsLabel setFrame:CGRectMake(CELL_CONTENT_MARGIN, CELL_CONTENT_MARGIN + NAME_CELL_HEIGHT, CELL_CONTENT_WIDTH - (CELL_CONTENT_MARGIN * 2), MAX(size.height, 44.0f))];

    // SETTING TEXT CONTENT
    cell.nameLabel.text = info.name;
    cell.ingredientsLabel.text = info.ingredients;

    // SETTING BACKGROUND COLOR

    //        UIView *lab = [[UIView alloc] initWithFrame:cell.frame];
    //        [lab setBackgroundColor:[UIColor blueColor]];

    if (myStore.cellBackgroundShouldBeLight == YES) {
        NSLog(@"clear? %@", myStore.cellBackgroundShouldBeLight ? @"Yes" : @"No");
        cell.contentView.backgroundColor = [[UIColor alloc]initWithRed:87.0/255.0 green:84.0/255.0 blue:229.0/255.0 alpha:1];
        //            cell.backgroundView = lab;
        //            ingredientsLabel.backgroundColor = [UIColor clearColor];
        //            nameLabel.backgroundColor = [[UIColor alloc]initWithRed:87.0/255.0 green:168.0/255.0 blue:229.0/255.0 alpha:1];
        //            [cell setBackgroundColor: [[UIColor alloc]initWithRed:87.0/255.0 green:168.0/255.0 blue:229.0/255.0 alpha:1]];
        //            [cell setBackgroundColor:[UIColor colorWithRed:.8 green:.8 blue:1 alpha:1]];
        myStore.cellBackgroundShouldBeLight = NO;
    } else {
//        cell.contentView.tag = 2;
        NSLog(@"clear? %@", myStore.cellBackgroundShouldBeLight ? @"Yes" : @"No");
        cell.contentView.backgroundColor = [[UIColor alloc]initWithRed:187.0/255.0 green:184.0/255.0 blue:229.0/255.0 alpha:1];
        myStore.cellBackgroundShouldBeLight = YES;
    }


    return cell;
}

Answer 1

这很简单，indexPath 告诉你你需要知道的一切。如果 indexPath.row 是偶数，则使用一种颜色。如果 indexPath.row 是奇数，则使用不同的颜色。

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

    // SETTING BACKGROUND COLOR

    //        UIView *lab = [[UIView alloc] initWithFrame:cell.frame];
    //        [lab setBackgroundColor:[UIColor blueColor]];

    if (indexPath.row % 2) {
        cell.contentView.backgroundColor = [[[UIColor alloc]initWithRed:87.0/255.0 green:84.0/255.0 blue:229.0/255.0 alpha:1] autorelease];
    } else {
        cell.contentView.backgroundColor = [[[UIColor alloc]initWithRed:187.0/255.0 green:184.0/255.0 blue:229.0/255.0 alpha:1] autorelease];
    }

    …

    return cell;
}

---

您的方法存在问题，因为盲目假设将交替要求细胞对是一个错误的假设。 tableView 可以按选择的任何顺序请求单元格。在您的示例中，我相信可以按如下方式要求单元格。首先，要求 0、1、…、9。接下来，您向下滚动并获取 10、11 和 12。此时，0、1 和 2 已离开屏幕。您向上滚动并要求输入 2，但是哦不，您的模型处于奇数交替状态，所以您得到了错误的颜色。