cellForRowAtIndexPath return nil

CustomTableCell * cell = [self.tableView cellForRowAtIndexPath:indexPath];

偶尔会返回nil，原因在于：An object representing a cell of the table, or nil if the cell is not visible or indexPath is out of range.所以当你的 cell 是不可见的时候就会返回nil

解决方法：重新获取

CustomTableCell * cell = [self.tableView cellForRowAtIndexPath:indexPath];
if (indexPath) {
    //定于到该行cell（此方法可以用于解决cell被遮挡的问题）
    [self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];
}
if (cell) {
    [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(indexPathForCell:) object:nil];
}else{
    [self performSelector:@selector(indexPathForCell:) withObject:indexPath afterDelay:.5];
}

- (void)indexPathForCell:(id)object {
    if ([object isKindOfClass:[NSIndexPath class]]) {
        NSIndexPath * indexPath = (NSIndexPath *)object;
        CustomTableCell * cell = [self.tableView cellForRowAtIndexPath:indexPath];
    }
}