NSString+TimeCategory

NSString+TimeCategory.h
//------------------------------------------------
#import <foundation foundation.h="">

@interface NSString (TimeCategory)
+ (NSString *)stringWithTime:(NSTimeInterval)time;
- (NSTimeInterval)timeValue;

@end
//------------------------------------------------
//NSString+TimeCategory.m
//------------------------------------------------
#import "NSString+TimeCategory.h"

@implementation NSString (TimeCategory)

+ (NSString *)stringWithTime:(NSTimeInterval)time {
    BOOL isPositive;
    NSInteger timeInt;

    if (time >  *  || time < -  * )
        return nil;
    if (time < ) {
        timeInt = (NSInteger)-time;
        isPositive = NO;
    } else {
        timeInt = (NSInteger)time;
        isPositive = YES;
    }

    NSInteger hour = timeInt/;
    NSInteger minute = (timeInt%)/;
    NSInteger second = (timeInt%)%;

    if (hour > ) {
        if (isPositive) {
            return [NSString stringWithFormat:@"%d%d:%d%d:%d%d",
hour/, hour%, minute/, minute%, second/, second%];
        } else {
            return [NSString stringWithFormat:@"-%d%d:%d%d:%d%d",
hour/, hour%, minute/, minute%, second/, second%];
        }

    } else {
        if (isPositive) {
            return [NSString stringWithFormat:@"%d%d:%d%d", minute/, minute%, second/, second%];
        } else {
            return [NSString stringWithFormat:@"-%d%d:%d%d", minute/, minute%, second/, second%];
        }

    }
}

- (NSTimeInterval)timeValue {
    NSInteger hour = , minute = , second = ;
    NSArray *sections = [self componentsSeparatedByString:@":"];
    NSInteger count = [sections count];
    second = [[sections objectAtIndex:count - ] integerValue];
    minute = [[sections objectAtIndex:count - ] integerValue];
    if (count > ) {
        hour = [[sections objectAtIndex:] integerValue];
    }
    return hour *  + minute *  + second;
}

@end
</foundation>