iphone - UITableView数据在滚动时多次显示

Question

我有一个 UITableView，其中显示数据，但当它滚动时，数据 (UILabel) 要么消失，要么一遍又一遍地叠加在一起。每次我滚动每个单元格时都会交换数据。

这是我的cellForRowAtIndexPath:代码

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
        static NSString *cellIdentifier = @"Cell";

        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];

        if(cell == nil) {
            cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];

        }

        cell.selectionStyle = UITableViewCellSelectionStyleNone;

        // configure the cell's background
        UIImageView *gradient = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"gradient"]];
        [cell.contentView addSubview:gradient];

        // configure the cell's label
        UILabel *nameLabel = [[UILabel alloc] initWithFrame:CGRectMake(50, 130, 300, 44)];

        // grab a reference to the label's text from the tableData
        nameLabel.text = [name objectAtIndex:indexPath.row];
        nameLabel.textColor = [UIColor blackColor];
        nameLabel.font = [UIFont fontWithName:@"DIN-Bold" size:12];
        nameLabel.backgroundColor = [UIColor clearColor];

        // set the autoReiszing mask -- this way if the label spills over the editing
        // [icon?] then the text will trail off in ...
        nameLabel.autoresizingMask = UIViewAutoresizingFlexibleWidth;

        [cell.contentView addSubview:nameLabel];

        // configure the cell's label
        UILabel *tableTextViewLbl = [[UILabel alloc] initWithFrame:CGRectMake(50, 80, 220, 50)];

        // grab a reference to the label's text from the tableData
        tableTextViewLbl.text = [message objectAtIndex:indexPath.row];
        tableTextViewLbl.textColor = [UIColor blackColor];
        tableTextViewLbl.font = [UIFont fontWithName:@"DIN" size:10];
        tableTextViewLbl.backgroundColor = [UIColor clearColor];
        tableTextViewLbl.autoresizingMask = UIViewAutoresizingFlexibleWidth;

        [cell.contentView addSubview:tableTextViewLbl];

        // configure the cell's label
        UILabel *tableTimeStampViewLbl = [[UILabel alloc] initWithFrame:CGRectMake(50, 30, 200, 50)];

        // grab a reference to the label's text from the tableData
        tableTimeStampViewLbl.text = [timeStamp objectAtIndex:indexPath.row];
        tableTimeStampViewLbl.textColor = [UIColor lightGrayColor];
        tableTimeStampViewLbl.font = [UIFont fontWithName:@"DIN" size:7];
        tableTimeStampViewLbl.backgroundColor = [UIColor clearColor];
        tableTimeStampViewLbl.autoresizingMask = UIViewAutoresizingFlexibleWidth;

        [cell.contentView addSubview:tableTimeStampViewLbl];

    //   UIImageView *image;
    //   UIImage *image1=[UIImage imageNamed:@"rest.png"];
    //   image=[[UIImageView alloc]initWithImage:image1];
    //   image.frame=CGRectMake(10,30,40,30);
    //   
    //   [cell.contentView addSubview:image];
    //


        return cell;

    }

Answer 1

每次将单元格加载/重新加载到 View 中时，您都会创建一个 UILabel 实例。这不是它的完成方式。相反 - 将 UILabel 作为属性(可能是 IBOutlet)添加到 UITableView 子类中，并在 cellForRowAtIndexPath: 中更改它。

所以你会有一个新类，继承自 UITableViewCell - 我们称它为 MyCustomCell。

在 MyCustomCell.h 中:

@interface MyCustomCell : UITableViewCell

@property (weak, nonatomic) IBOutlet UILabel *nameLabel;

@end

MyCustomCell.xib会定义UILabel的位置和配置，当然需要关联nameLabel属性。

在 cellForRowAtIndexPath 中，无需实例化新的 UILabel，您只需引用 cell.nameLabel 并更改文本。请务必在界面生成器中为单元类定义一个 resuseIdentifier 并使用以下方法实例化它:

MyCustomCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MyIdentifier"];

if (!cell) {
    cell = [[MyCustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"MyIdentifier"];

}