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 > 3600 * 24 || time < - 3600 * 24)
        return nil;
    if (time < 0) {
        timeInt = (NSInteger)-time;
        isPositive = NO;
    } else {
        timeInt = (NSInteger)time;
        isPositive = YES;
    }
 
 
    NSInteger hour = timeInt/3600;
    NSInteger minute = (timeInt%3600)/60;
    NSInteger second = (timeInt%3600)%60;
 
    if (hour > 0) {
        if (isPositive) {
            return [NSString stringWithFormat:@"%d%d:%d%d:%d%d", 
hour/10, hour%10, minute/10, minute%10, second/10, second%10];
        } else {
            return [NSString stringWithFormat:@"-%d%d:%d%d:%d%d", 
hour/10, hour%10, minute/10, minute%10, second/10, second%10];
        }
 
    } else {
        if (isPositive) {
            return [NSString stringWithFormat:@"%d%d:%d%d", minute/10, minute%10, second/10, second%10];
        } else {
            return [NSString stringWithFormat:@"-%d%d:%d%d", minute/10, minute%10, second/10, second%10];
        }
 
    }
}
 
- (NSTimeInterval)timeValue {
    NSInteger hour = 0, minute = 0, second = 0;
    NSArray *sections = [self componentsSeparatedByString:@":"];
    NSInteger count = [sections count];
    second = [[sections objectAtIndex:count - 1] integerValue];
    minute = [[sections objectAtIndex:count - 2] integerValue];
    if (count > 2) {
        hour = [[sections objectAtIndex:0] integerValue];
    }
    return hour * 3600 + minute * 60 + second;
}
 
@end
</foundation>