objective-c - 如果不使用 indexpath

Question

我想知道为什么这不起作用，请帮助我。这是我的代码

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath 

*)indexPath
{
    if (selectedIndexPath == indexPath) {
        selectedIndexPath = nil;
    } else {
        selectedIndexPath = indexPath;
    }
    [self.tableView deselectRowAtIndexPath : indexPath animated : NO];
    [tableView beginUpdates];
    [tableView endUpdates];
}

Answer 1

确保保留您的selectedIndexPath，以免nil无意中设置为。

@interface YourClass

@property (nonatomic, strong) NSIndexPath *selectedIndexPath;

@end

然后将变量引用为self.selectedIndexPath，你应该没问题。

但还有第二个警告。NSIndexPath是一个对象，因此运算符==将只比较指针地址。显然，这些总是不同的，因为一个是你的变量，另一个是方法的私有变量！你想要使用的是

if ([indexPath isEqualTo:selectedIndexPath]) // not tested

或者

if (indexPath.row == selectedIndexPath.row && 
    indexPath.section == selectedIndexPath.section)

Answer 2

NSIndexPath object consists of two parts they are row and section. The indexPathForRow:inSection: method creates an NSIndexPath object from row and section index numbers. Make sure your selectedIndexPath is created properly. Follow this apple reference for more details.