1：根据生日计算年龄
```
NSString * birthStr = @"1991-07-13";
NSDateFormatter * formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"yyyy-MM-dd";
NSDate * birthDate = [formatter dateFromString:birthStr];
NSTimeInterval dateDiff = [birthDate timeIntervalSinceNow];
计算年龄
int age1 = trunc(dateDiff/(60*60*24))/365;
```
2：根据生日计算星座
```
-(NSString *)calculateConstellationWithMonth:(NSInteger)month day:(NSInteger)day
{
NSString *astroString = @"魔羯水瓶双鱼白羊金牛双子巨蟹狮子处女天秤天蝎射手魔羯";
NSString *astroFormat = @"102123444543";
NSString *result;
if (month<1 || month>12 || day<1 || day>31){
return @"错误日期格式!";
}
```
if(month==2 && day>29)
{
return @"错误日期格式!!";
}else if(month==4 || month==6 || month==9 || month==11) {
if (day>30) {
return @"错误日期格式!!!";
}
}
result=[NSString stringWithFormat:@"%@",[astroString substringWithRange:NSMakeRange(month*2-(day < [[astroFormat substringWithRange:NSMakeRange((month-1), 1)] intValue] - (-19))*2,2)]];
return [NSString stringWithFormat:@"%@座",result];
}
