Question

我有一个应用程序需要异步更新某些列中的单元格。我有一个GCD队列，其中添加了块，稍后使用-rowForItem:获取行和列的单元格，但-rowForItem:的结果始终为0，并且NSAssert([self.outlineView itemAtRow:row] == item, @"rowForItem: and itemForRow: not reversible! (Item %@, row %ld)", item, (long)row);每次都会抛出。我不知道我在这里做错了什么。索引不是-1，这意味着找不到该项，但该项被认为是不正确的索引。（第一项始终是JODirectoryInfo，我只在JOFileInfo上运行块，因此它不能是错误的项目。）

- (NSTableCellView *)_cellForRow:(NSInteger)row columnIdentifier:(NSString *)column {
    if (row < 0) return nil;
    NSInteger colIdx = [self.outlineView columnWithIdentifier:column];
    if (colIdx == -1) return nil;
    if (colIdx + 1 > self.outlineView.tableColumns.count) return nil;
    return [self.outlineView viewAtColumn:colIdx row:row makeIfNecessary:NO];
}
- (NSTableCellView *)_cellForItem:(id)item columnIdentifier:(NSString *)column {
    NSInteger row = [self.outlineView rowForItem:item];
    NSAssert([self.outlineView itemAtRow:row] == item, @"rowForItem: and itemForRow: not reversible! (Item %@, row %ld)", item, (long)row);
    DDLogVerbose(@"Getting cell for item %@ (row %ld) in column %@", item, (long)row, column);
    return [self _cellForRow:row columnIdentifier:column];
}

- (dispatch_block_t)_loadingBlockForItem:(JOFileInfo *)item block:(JOFileInfoBlock)block column:(NSString *)columnIdentifier {
    return ^{
        NSTableCellView *cellView = [self _cellForItem:item columnIdentifier:columnIdentifier];
        if (!cellView) return;
        cellView.objectValue = block(item);
    };
}
- (id)outlineView:(NSOutlineView *)outlineView objectValueForTableColumn:(NSTableColumn *)tableColumn byItem:(id)item {
    DDLogVerbose(@"Requested value of column %@ for item %@", tableColumn.identifier, item);
    if ([tableColumn.identifier isEqualToString:@"Size"]) {
        if ([item isKindOfClass:[JOFileInfo class]]) {
            dispatch_async(self.queue, [self _loadingBlockForItem:item block:^(JOFileInfo *item) {
                unsigned long long size = item.size;
                if (size != ULONG_LONG_MAX) return [self.byteCountFormatter stringFromByteCount:size];
                else return @"--";
            } column:tableColumn.identifier]);
            return @"--";
        } else {
            return @"--";
        }
    } else {
        return @"text";
    }
}

Answer 1

它返回零，因为大纲视图为零。

NSOutlineView rowForItem：始终返回0

1 个答案: