UITableViewCell 子类导致无法识别的选择器发送问题

Question

我正在对 UITableViewCell 进行子类化，这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我绘制，所以我在搜索后找到的答案是一个子类，但我有一些问题。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;
}

还有我的 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 **在顶部重新绘制单元格

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

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，我想我现在明白问题所在了。您使用的 dequeueReusableCellWithIdentifier:forIndexPath: 是新的 iOS 6 并且设计为从不 return 零单元格（以防止应用程序崩溃和开发人员方便）。因此，您后面的 if 语句适用于 OLD dequeue 方法，它只是 dequeueReusableCellWithIdentifier

修复应该改变这个：

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

对此：

cell = [tableView dequeueReusableCellWithIdentifier:requestCell];

more details can be found here

Answer 2

如果您的单元格是在情节提要中制作的，那么 initWithCoder: 是调用的 init 方法，而不是 initWithStyle:reuseIdentifier:。所以，重写它，创建你的标签，然后将它们添加到那里的 contentView 中。此外，没有理由在您的 cellForRowAtIndexPath 方法中使用 if cell == nil 子句，因为您的 dequeue 方法保证 return 一个单元格。

你应该改变的另一件事是，

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

您在第一行中实例化了一个 Request 对象，但随后在下一行中将其重新定义为 self.isNotFilledList[indexPath.row] 并将其丢弃。你应该有，

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

UITableViewCell 子类导致无法识别的选择器发送问题

UITableViewCell subclass causing unrecognized selector sent issue

objective-c

uitableview

ios