The following code is to convert day into specific day of week like Sunday , Monday , today , tomorrow etc. and after 7 days you want to show only that date, then this code will help you.

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"dd-MM-yy"];
    serDate = datePicker.date;
    endDate = [NSDate date];

    NSTimeInterval distanceBetweenDates = [serDate timeIntervalSinceDate:endDate];
    double secondsInAnHour = 3600;
    NSInteger hoursBetweenDates = distanceBetweenDates / secondsInAnHour;
    NSLog(@"time slice == %d",hoursBetweenDates);

    if ((hoursBetweenDates <= -24)&&(hoursBetweenDates >= -48)) {
        dateText.text = @"Yesterday";
    }else if ((hoursBetweenDates >= -24)&&(hoursBetweenDates <= 0)){
        dateText.text = @"Today";
    }else if ((hoursBetweenDates > 0)&&(hoursBetweenDates <= 24)){
        dateText.text = @"Tomorrow";
    }else if ((hoursBetweenDates >= 24)&&(hoursBetweenDates <= 148)){
        dateText.text = [self stringFromDate:serDate format:@"EEEE"];
    }else{

        dateText.text = [self stringFromDate:serDate format:@"dd-MM-yy"];
    }