NSTimeInterval time = [[NSDate date] timeIntervalSince1970]; 可以这样定义

NSLog(@"当前时间为%f", time); 打印出从1970年开始到现在的秒数。

可见time可以赋值给float类型

所以可以这样写：

float a ＝ time；

这样就可以很容易的到两个时间点中间相差多少秒。

第一种方式：

NSTimeInterval time = 。。。;

NSString *string = [NSString stringWithFormat:@"%02li:%02li:%02li",

lround(floor(time / 3600。)) % 100,

lround(floor(time / 60。)) % 60,

lround(floor(time。)) % 60];

第二种方式：

// You could also have stored the start time using

// CFAbsoluteTimeGetCurrent()

NSTimeInterval elapsedTime = [startDate timeIntervalSinceNow];

// Divide the interval by 3600 and keep the quotient and remainder

p_t h = p(elapsedTime, 3600);

int hours = h。quot;

// Divide the remainder by 60; the quotient is minutes, the remainder

// is seconds。

p_t m = p(h。rem, 60);

int minutes = m。quot;

int seconds = m。rem;

// If you want to get the inpidual digits of the units, use p again

// with a pisor of 10。

NSLog(@"%d:%d:%d", hours, minutes, seconds)

如果您有您初始日期存储在 NSDate 对象时，您可以获得新日期任何时间间隔在未来。只需使用 dateByAddingTimeInterval: 像这样：

NSDate * originalDate = [NSDate date];

NSTimeInterval interval = 1;

NSDate * futureDate = [originalDate dateByAddingTimeInterval:interval];

ios获取自1970年以来的毫秒数同java的System。currentTimeMillis()

示例代码

// The time interval 

NSTimeInterval theTimeInterval = 326。4;

// Get the system calendar

NSCalendar *sysCalendar = [NSCalendar currentCalendar];

// Create the NSDates

NSDate *date1 = [[NSDate alloc] init];

NSDate *date2 = [[NSDate alloc] initWithTimeInterval:theTimeInterval sinceDate:date1]; 

// Get conversion to months, days, hours, minutes

unsigned int unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit;

NSDateComponents *conversionInfo = [sysCalendar components:unitFlags fromDate:date1  toDate:date2  options:0];

NSLog(@"Conversion: %dmin %dhours %ddays %dmoths",[conversionInfo minute], [conversionInfo hour], [conversionInfo day], [conversionInfo month]);

[date1 release];

[date2 release];