NSTimeInterval本身是个秒级别的double类型数值，小数点后面即毫秒数
时间差
- (NSString *)intervalSinceNow: (NSString *) theDate
{
NSDateFormatter *date=[[NSDateFormatter alloc] init];
[date setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSDate *d=[date dateFromString:theDate];
NSTimeInterval late=[d timeIntervalSince1970]*1;
NSDate* dat = [NSDate dateWithTimeIntervalSinceNow:0];
NSTimeInterval now=[dat timeIntervalSince1970]*1;
NSString *timeString=@"";
NSTimeInterval cha=now-late;
if (cha/3600<1) {
timeString = [NSString stringWithFormat:@"%f", cha/60];
timeString = [timeString substringToIndex:timeString.length-7];
timeString=[NSString stringWithFormat:@"%@分钟前", timeString];
}
if (cha/3600>1&&cha/86400<1) {
timeString = [NSString stringWithFormat:@"%f", cha/3600];
timeString = [timeString substringToIndex:timeString.length-7];
timeString=[NSString stringWithFormat:@"%@小时前", timeString];
}
if (cha/86400>1)
{
timeString = [NSString stringWithFormat:@"%f", cha/86400];
timeString = [timeString substringToIndex:timeString.length-7];
timeString=[NSString stringWithFormat:@"%@天前", timeString];
}
[date release];
return timeString;
}
+(BOOL)intervalSinceNow:(NSDate *)beforeData{
//NSData *beafte=[[NSData alloc] initWithData:beforeData];
NSTimeInterval before = [beforeData timeIntervalSince1970]*1;
NSDate *datTime = [NSDate date];
NSTimeInterval nowTime = [dat timeIntervalSince1970]*1;
NSTimeInterval cha = nowTime - before;
if(cha/3600 < 1){
return YES;
}
return NO;
}
时间 格式化用
在开发iOS程序时，有时候需要将时间格式调整成自己希望的格式，这个时候我们可以用NSDateFormatter类来处理。
例如：
//实例化一个NSDateFormatter对象
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
//设定时间格式,这里可以设置成自己需要的格式
[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
//用[NSDate date]可以获取系统当前时间
NSString *currentDateStr = [dateFormatter stringFromDate:[NSDate date]];
//输出格式为：2010-10-27 10:22:13
NSLog(@”%@”,currentDateStr);
//alloc后对不使用的对象别忘了release
[dateFormatter release];