Question

我是UITableViewCell的子类，它导致我的应用程序崩溃...我遇到的问题是我的单元格一直在自己绘制，所以我在搜索后找到的答案是子类，但我遇到了一些问题。这是我的代码。

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


    static NSString *requestCell = @"requestCell";

    RequestCell *cell;

    switch (indexPath.section) {
        {case 0:
            cell = [tableView dequeueReusableCellWithIdentifier:requestCell forIndexPath:indexPath];
            if (cell == nil) {
                cell = [[RequestCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:requestCell];
            }

            //APP CRASHES ON THIS LINE 
            cell.requestTitle.frame = CGRectMake(60, 5, self.view.frame.size.width - 70, 30);
            cell.detailTitle.frame = CGRectMake(60, 30, self.view.frame.size.width - 70, 25);

            Request *request = [[Request alloc] init];
            request = self.isNotFilledList[indexPath.row];
            cell.requestTitle.text = request.productName;
            cell.detailTitle.text = request.dateRequested;
            cell.detailTitle.font = [UIFont systemFontOfSize:11.0];

            NSString *imageURL = @"myurl";
            imageURL = [imageURL stringByAppendingString:request.productImageName];

            cell.requestImageButton.frame = CGRectMake(5, 5, 50, 50);
            [cell.requestImageButton sd_setBackgroundImageWithURL:[NSURL URLWithString:imageURL] forState:UIControlStateNormal];

            NSLog(@"request name %@", request.productName);
            return cell;
        break;}

        {case 1:
            cell = [tableView dequeueReusableCellWithIdentifier:requestCell forIndexPath:indexPath];
            if (cell == nil) {
                cell = [[RequestCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:requestCell];
            }

            Request *request = [[Request alloc] init];
            request = [self.isFilledList objectAtIndex:indexPath.row];
            cell.textLabel.text = request.productName;
            return cell;
            break;}

        default:
            break;
    }

    return cell;
}

我的RequestCell类

@interface RequestCell : UITableViewCell

@property (strong, nonatomic) UILabel *requestTitle;
@property (strong, nonatomic) UILabel *detailTitle;
@property (strong, nonatomic) UIButton *requestImageButton;

和.m文件

#import "RequestCell.h"

@implementation RequestCell

- (void)awakeFromNib {
    // Initialization code
}

-(id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {


    }
    return self;
}

-(UILabel *)requestTitle
{
    if(!_requestTitle)
    {
        _requestTitle = [[UILabel alloc] init];
    }
    return _requestTitle;
}

-(UILabel *)detailTitle
{
    if(!_detailTitle)
    {
        _detailTitle = [[UILabel alloc] init];
    }
    return _detailTitle;
}


-(UIButton *)requestImageButton
{
    if(!_requestImageButton)
    {
        _requestImageButton = [[UIButton alloc] init];
    }
    return _requestImageButton;
}



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

    // Configure the view for the selected state
}

我做错了什么???

原始代码**重新绘制顶部的单元格

switch (indexPath.section) {
        {case 0:
            cell = [tableView dequeueReusableCellWithIdentifier:requestCell forIndexPath:indexPath];
            if (cell == nil) {
                cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:requestCell];
            }

            UILabel *title = [[UILabel alloc] initWithFrame:CGRectMake(55, 5, self.view.frame.size.width - 60, 30)];
            UILabel *detailTitle = [[UILabel alloc] initWithFrame:CGRectMake(55, 30, self.view.frame.size.width - 60, 25)];

            Request *request = [[Request alloc] init];
            request = self.isNotFilledList[indexPath.row];
            title.text = request.productName;
            detailTitle.text = request.dateRequested;

            NSString *imageURL = @"myurl";
            imageURL = [imageURL stringByAppendingString:request.productImageName];

            UIButton *keyImageButton = [[UIButton alloc] initWithFrame:CGRectMake(5, 5, 50, 50)];
            //[[keyImageButton imageView] setContentMode: UIViewContentModeScaleAspectFill];
            [keyImageButton sd_setBackgroundImageWithURL:[NSURL URLWithString:imageURL] forState:UIControlStateNormal];

            [cell addSubview:detailTitle];
            [cell addSubview:title];
            [cell addSubview:keyImageButton];

            NSLog(@"request name %@", request.productName);
            return cell;
        break;}

Answer 1

如果您的单元格是在故事板中制作的，那么initWithCoder:是调用的init方法，而不是initWithStyle:reuseIdentifier:。因此，覆盖它，并创建标签，并将它们添加到contentView。此外，没有理由在cellForRowAtIndexPath方法中使用if cell == nil子句，因为您的出队方法可以保证返回一个单元格。

你应该改变的另一件事就是这个，

Request *request = [[Request alloc] init];
request = self.isNotFilledList[indexPath.row];

您在第一行中实例化一个Request对象，但随后通过在下一行中将其重新定义为self.isNotFilledList [indexPath.row]来抛弃它。你应该有，

Request *request = self.isNotFilledList[indexPath.row];

Answer 2

您不需要手动实例化Cell实例变量。尝试删除额外的功能

-(UILabel *)requestTitle
{
    if(!_requestTitle)
    {
        _requestTitle = [[UILabel alloc] init];
    }
    return _requestTitle;
}

-(UILabel *)detailTitle
{
    if(!_detailTitle)
    {
        _detailTitle = [[UILabel alloc] init];
    }
    return _detailTitle;
}


-(UIButton *)requestImageButton
{
    if(!_requestImageButton)
    {
        _requestImageButton = [[UIButton alloc] init];
    }
    return _requestImageButton;
}

赞成这个

@implementation RequestCell
@synethesize requestTitle;
@synthesize detailTitle;
@synthesize requestImageButton;

编辑：

啊我觉得我现在看到了问题。您正在使用dequeueReusableCellWithIdentifier:forIndexPath:这是新的iOS 6并且设计为永远不会返回nil单元格（以防止应用程序崩溃和开发人员的便利）。所以你的if语句是针对OLD出列方法的，它只是dequeueReusableCellWithIdentifier

修复应该改变这个：

cell = [tableView dequeueReusableCellWithIdentifier:requestCell forIndexPath:indexPath];

到此：

cell = [tableView dequeueReusableCellWithIdentifier:requestCell];

more details can be found here

UITableViewCell子类导致无法识别的选择器发送问题

2 个答案: