Question

     cell.theTitle.font=[UIFont fontWithName:@"Helvetical Bold" size:14];
     cell.theTitle.text =[NSString stringWithFormat:@"%@",theCellData.contentTitle];
 cell.theDescriptionLabel.text=theCellData.contentTitle;
 cell.theDateAdded.text=[NSString stringWithFormat:@"Added: %@",theCellData.contentAddedDateTime];


 NSString*type=theCellData.contentType;


 NSLog(@"type is %@",type);


 if ([type isEqualToString:@"Video"]) {

     [cell.theCellImageButton setImage:[UIImage imageNamed:[NSString stringWithFormat:@"Video icon.png",indexPath.row]] forState:UIControlStateNormal];


 }
else if ([type isEqualToString:@"Audio"]) {




    NSLog(@"Audio");
      [cell.theCellImageButton setImage:[UIImage imageNamed:[NSString stringWithFormat:@"Sound icon.png",indexPath.row]] forState:UIControlStateNormal];


}
else {


    [cell.theCellImageButton setImage:[UIImage imageNamed:[NSString stringWithFormat:@"20.png",indexPath.row]] forState:UIControlStateNormal];


}




[cell.theCellImageButton addTarget:self action:@selector(imageButtonAction:) forControlEvents:UIControlEventTouchUpInside];

[cell.theCellImageButton setTag:indexPath.row];




 return cell;

这是崩溃日志

类型是音频 2013-06-14 16：09：50.071 ProductivoApp [6516：c503]音频 2013-06-14 16：09：50.076 ProductivoApp [6516：c503] - [NSNull isEqualToString：]：无法识别的选择器发送到实例0x125adc8 2013-06-14 16：09：50.079 ProductivoApp [6516：c503] * 由于未捕获的异常'NSInvalidArgumentException'而终止应用程序，原因：' - [NSNull isEqualToString：]：无法识别的选择器发送到实例0x125adc8 “

Answer 1

您的字符串获取空值。因此在比较变量类型时显示错误

 NSString*type=theCellData.contentType;// is null
if ([type isEqualToString:@"Video"]) //error at this line

Answer 2

您要比较的字符串为空。尝试添加： //只有在不为空时才会这样做 if（string）{

if（[type isEqualToString：@＆＃34; Video＆＃34;]）{

 [cell.theCellImageButton setImage:[UIImage imageNamed:[NSString stringWithFormat:@"Video icon.png",indexPath.row]] forState:UIControlStateNormal];

} else if（[type isEqualToString：@＆＃34; Audio＆＃34;]）{

NSLog(@"Audio");
  [cell.theCellImageButton setImage:[UIImage imageNamed:[NSString stringWithFormat:@"Sound icon.png",indexPath.row]] forState:UIControlStateNormal];

} 别的{

[cell.theCellImageButton setImage:[UIImage imageNamed:[NSString stringWithFormat:@"20.png",indexPath.row]] forState:UIControlStateNormal];

}

这将确保不会发生空比较

Answer 3

您的type字符串不等于Audio或Video。当发生崩溃时，类型指的是NSNull的实例。有关详细信息，请尝试打印此文件，您将获得此NSNull。

NSLog(@"%@", [type class]);

索引中Cell for Row的iphone应用程序中的NSNull异常

3 个答案: