objective-c - 在 UITableview 中加载数据问题

Question

我使用 UITableView 创建了一个应用程序。我从 URL 解析数据并在 UITableView 中列出。

但在 UITableView 中，第一个数据只是一次又一次地显示。

我不知道为什么会出现这个问题。

我的代码如下:

-(UITableViewCell *)tableView:(UITableView *)tableView1 cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView1 dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil)
    {
    cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
    [cell setSelectionStyle:UITableViewCellSelectionStyleNone];
    CGRect frame = CGRectMake(10.0f, 5.0, 300.0, 55);
    valueField = [[UILabel alloc] initWithFrame:frame];
    [valueField setAutoresizingMask:UIViewAutoresizingFlexibleLeftMargin];
    valueField.tag = 111;
    valueField.font=[UIFont fontWithName:@"Helvetica" size:16.0];
    valueField.textAlignment = UITextAlignmentLeft;
    valueField.lineBreakMode=UILineBreakModeWordWrap;
    valueField.numberOfLines = 0;
    valueField.textColor = [UIColor whiteColor];
    valueField.highlightedTextColor = [UIColor whiteColor];
    valueField.baselineAdjustment = UIBaselineAdjustmentAlignCenters;
    valueField.adjustsFontSizeToFitWidth = YES;
    valueField.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];
    valueField.text=[title1 objectAtIndex:count1];
    [cell.contentView addSubview:valueField];
    UIImage *favOn = [UIImage imageNamed:@""];
    UIImage *favOff = [UIImage imageNamed:@""];                   
    titlebutton = [[UIButton alloc] initWithFrame:CGRectMake(10.0f, 15.0, 300.0, 55)];
    [titlebutton setTag:indexPath.row];
    //titlebutton.tag = 111;
    [titlebutton setImage:favOff forState:UIControlStateNormal];
    [titlebutton setImage:favOn forState:UIControlStateSelected];
    if([self getFavState:@"111"]) 
    {
        [titlebutton setSelected:YES];
    }
    else 
    {
        [titlebutton setSelected:NO];
    }
    [titlebutton addTarget:self action:@selector(favButtonSwitch:) forControlEvents:UIControlEventTouchUpInside];
    [titlebutton setBackgroundColor:[UIColor clearColor]];
    [titlebutton setTitle:@"" forState:UIControlStateNormal];
    [cell.contentView addSubview:titlebutton];
    CGSize labelSize = [valueField.text sizeWithFont:valueField.font constrainedToSize:valueField.frame.size lineBreakMode:UILineBreakModeWordWrap];
    int labelHeight = labelSize.height;
    NSLog(@"labelHeight = %d", labelHeight);

    frame = CGRectMake(10.0f, 40.0, 300.0, 55);
    pubField = [[UILabel alloc] initWithFrame:frame];
    [pubField setAutoresizingMask:UIViewAutoresizingFlexibleLeftMargin];
    pubField.tag = 111;
    pubField.font=[UIFont fontWithName:@"Helvetica" size:12.0];
    pubField.textAlignment = UITextAlignmentLeft;
    pubField.lineBreakMode=UILineBreakModeWordWrap;
    pubField.numberOfLines = 0;
    pubField.textColor = [UIColor whiteColor];
    pubField.highlightedTextColor = [UIColor whiteColor];
    pubField.baselineAdjustment = UIBaselineAdjustmentAlignCenters;
    pubField.adjustsFontSizeToFitWidth = YES;
    pubField.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];
    pubField.text=[pubDate objectAtIndex:indexPath.row];
    [cell.contentView addSubview:pubField];

    frame = CGRectMake(5.0, 70.0, 300.0, 55);
    desField = [[UILabel alloc] initWithFrame:frame];
    [desField setAutoresizingMask:UIViewAutoresizingFlexibleLeftMargin];
    desField.tag = 111;
    desField.font=[UIFont fontWithName:@"Helvetica" size:13.0];
    desField.textAlignment = UITextAlignmentLeft;
    desField.lineBreakMode=UILineBreakModeWordWrap;
    desField.numberOfLines = 0;
    desField.textColor = [UIColor whiteColor];
    desField.highlightedTextColor = [UIColor whiteColor];
    desField.baselineAdjustment = UIBaselineAdjustmentAlignCenters;
    desField.adjustsFontSizeToFitWidth = YES;
    desField.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];
    desField.text=[description objectAtIndex:indexPath.row];
    [cell.contentView addSubview:desField];
    }

    UIImage *patternImage = [UIImage imageNamed:@"bg.jpg"];
    UIView *backView = [[[UIView alloc] initWithFrame:CGRectZero] autorelease];
    backView.backgroundColor = [UIColor colorWithPatternImage: patternImage];
    cell.backgroundView = backView;

    NSString *image1 =[images objectAtIndex:indexPath.row];
    NSLog(@"Images  .....   = %@",image1);
    NSData *mydata = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:[images objectAtIndex:indexPath.row]]];
    UIImage *myimage = [[UIImage alloc] initWithData:mydata];
    UIImageView *imageView = [ [ UIImageView alloc ] initWithImage: myimage ];
    imageView.frame = CGRectMake(10.0f, 110.0f, 120.0f, 120.0f); 
    [cell.contentView addSubview:imageView];
    return cell;
    }

Answer 1

执行所有 alloc/init 和所有事情，这在

中的任何单元格中都是相同的

if(cell==nil){
    //<-- here
}

同时设置文本和任何由 block 外的特定数据改变的东西

if(cell==nil){

}
//<-- here

即:

if(cell==nil){
    //....
    valueField.tag = 111;
    valueField.font = [UIFont fontWithName:@ "Helvetica" size:16.0];
    valueField.textAlignment = UITextAlignmentLeft;
    valueField.lineBreakMode = UILineBreakModeWordWrap;
    valueField.numberOfLines = 0;
    valueField.textColor = [UIColor whiteColor];
    valueField.highlightedTextColor = [UIColor whiteColor];
    valueField.baselineAdjustment = UIBaselineAdjustmentAlignCenters;
    valueField.adjustsFontSizeToFitWidth = YES;
    valueField.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];
    [cell.contentView addSubview : valueField];
    //....
}
//....
valueField.text = [title1 objectAtIndex:count1];
//....