IOS8 NSInvalidArgumentException发送到实例的无法识别的选择器

Question

我的应用程序曾用于ios5到ios7。最近我尝试使用xcode6和simulator8在ios8上运行。该应用程序崩溃了。我发现异常＆＃34; NSInvalidArgumentException，原因 - [UILabel selectedSegmentIndex]无法识别的选择器发送到实例＆＃34;当它达到[[self weightUnitsc_s] setSelectedSegmentIndex：0];

时

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
tableView.separatorColor=[UIColor colorWithRed:0 green:0.5765 blue:0.4431 alpha:1];

static NSString *CellIdentifier = @"Cell";

//UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];


if (indexPath.section==0){
    if (indexPath.row==0){
        weight * cell=(weight *)[tableView dequeueReusableCellWithIdentifier:@"weightcell"];
        if (cell == nil) {
            NSLog(@"weight nil");
            NSArray* arr=[[NSBundle mainBundle] loadNibNamed:@"weight" owner:self options:nil];
            cell= [arr objectAtIndex:0];
            [[cell weightUnitsc] setFrame:CGRectMake(cell.weightUnitsc.frame.origin.x, cell.weightUnitsc.frame.origin.y+5, cell.weightUnitsc.frame.size.width, 30)];
            [[cell weightUnitsc] addTarget:self action:@selector(segChange2) forControlEvents:UIControlEventValueChanged];

        }
        [cell LabelText:[Language get:@"setting.weightUnit" alter:@""]];
        [cell SegText:[Language get:@"setting.weightUnit.kg" alter:@""] :0];
        [cell SegText:[Language get:@"setting.weightUnit.g" alter:@""] :1];
        [cell SegText:[Language get:@"setting.weightUnit.lbs" alter:@""] :2];
        [cell SegText:[Language get:@"setting.weightUnit.oz" alter:@""] :3];


        [self setWeightUnitsc_s:[cell.contentView.subviews objectAtIndex:1]];
        switch ([WeightUnit getCurrentWeightID]) {
            case 1:
                [[self weightUnitsc_s] setSelectedSegmentIndex:1];
                break;
            case 2:
                [[self weightUnitsc_s] setSelectedSegmentIndex:2];
                break;
            case 3:
                [[self weightUnitsc_s] setSelectedSegmentIndex:3];
                break;
            default:
                [[self weightUnitsc_s] setSelectedSegmentIndex:0];
                break;
        }
        cell.selectionStyle=UITableViewCellSelectionStyleNone;

        [cell setBackgroundView:[[[UACellBackgroundView alloc] init] autorelease]];
        [(UACellBackgroundView *)[cell backgroundView] setPosition:UACellBackgroundViewPositionTop];

        return cell;
    }

有人可以帮忙解释并解决问题吗？谢谢。