iOS 计算两个时间差

-(NSString *)dateTimeDifferenceWithStartTime:(NSString *)startTime endTime:(NSString *)endTime{

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

[date setDateFormat:@"yyyy-MM-dd HH:mm:ss"];

NSDate *startD =[date dateFromString:startTime];

NSDate *endD = [date dateFromString:endTime];

NSTimeInterval start = [startD timeIntervalSince1970]*1;

NSTimeInterval end = [endD timeIntervalSince1970]*1;

NSTimeInterval value = end - start;

int second = (int)value %60;//秒

int minute = (int)value /60%60;

int house = (int)value % (24 * 3600)/3600;

int day = (int)value / (24 * 3600);

NSString *str;

if (day != 0) {

str = [NSString stringWithFormat:@"耗时%d天%d小时%d分%d秒",day,house,minute,second];

}else if (day==0 && house != 0) {

str = [NSString stringWithFormat:@"耗时%d小时%d分%d秒",house,minute,second];

}else if (day== 0 && house== 0 && minute!=0) {

str = [NSString stringWithFormat:@"耗时%d分%d秒",minute,second];

}else{

str = [NSString stringWithFormat:@"耗时%d秒",second];

}

return str;

}