选择日期计算出星期几

-(NSString *)getTheDayOfTheWeekByDateString:(NSString *)dateString{

    

    NSDateFormatter *inputFormatter=[[NSDateFormatter alloc]init];

    

    [inputFormatter setDateFormat:@"yyyy-MM-dd"];

    

    NSDate *formatterDate=[inputFormatter dateFromString:dateString];

    

    NSDateFormatter *outputFormatter=[[NSDateFormatter alloc]init];

    

    [outputFormatter setDateFormat:@"EEEE-MMMM-d"];

    

    NSString *outputDateStr=[outputFormatter stringFromDate:formatterDate];

    

    NSArray *weekArray=[outputDateStr componentsSeparatedByString:@"-"];

    

    return [weekArray objectAtIndex:0];

}

//    NSLog(@"2018-02-13==%@",[self getTheDayOfTheWeekByDateString:@"2018-02-13"]);

//    NSLog(@"2018-05-12==%@",[self getTheDayOfTheWeekByDateString:@"2018-05-12"]);

//    NSLog(@"2018-07-17==%@",[self getTheDayOfTheWeekByDateString:@"2018-07-17"]);

//    NSLog(@"2018-02-12==%@",[self getTheDayOfTheWeekByDateString:@"2018-02-12"]);

//    NSLog(@"2018-01-31==%@",[self getTheDayOfTheWeekByDateString:@"2018-01-31"]);