获取某一天是星期几的demo

NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];
[inputFormatter setDateFormat:@"yyyy-MM-dd 'at' HH:mm"];

NSDate *formatterDate = [inputFormatter dateFromString:@"2015-10-11 at 09:30"];//这里的string是你想要获取的日期，如果想要获取当前时间可以  NSDate *date = [NSdate date];

NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];
[outputFormatter setDateFormat:@"HH:mm 'on' EEEE MMMM d"];

NSString *newDateString = [outputFormatter stringFromDate:formatterDate];

NSLog(@"newDateString %@", newDateString);