cell设置不重用
staticNSString *CellIdentifier = @"_issuFellCell";
_issuFellCell= [tableView cellForRowAtIndexPath:indexPath];
if (!_issuFellCell) {
_issuFellCell = [[IssueInfoTableViewCellalloc]initWithStyle:UITableViewCellStyleSubtitlereuseIdentifier:CellIdentifier];
}