d %f seconds ago",timeBetweenDates);
NSCalendar *systemCalendar =[NSCalendar currentCalendar];
unsigned int uniFlags=NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit|NSDayCalendarUnit；
NSDateComponents *dateComparisonComponents = [systemCalendar components:unitFlags fromDate:iPoneReleaseDate toDate:todaysDate options:NSWrapCalendarComponents];
NSLog(@"The iPone was released %ld years,%ld months and %ld days ago",dateComparisonComponents.year,dateComparisonComponents.month,dateComparisonComponents.day);
}
return 0;
}
/**
*将字符串转换为日期
*/
//NSDateFormatter
NSString *dateString=@"02/14/2012"
NSDateFormatter *df=[[NSDateFormatter alloc]init];//创建格式化类对象
df.dateFormat=@"MM/dd/yyyy";//设置字符串格式
NSDate *valentinesDay=[df dateFromString:dateString];//执行转换字符串函数将字符串转换为date类型
/**
*日期转换例子
*/
import
int main(int argc,const char *argv[]){
@autoreleasepooll{
NSString *dateString=@"02/14/2012";
NSDateFormatter *df=[[NSDateFormatter alloc]init];
df.dateFormat=@"MM/dd/yyyy";
NSDate *valentinesDay=[df dateFromString:dateString];
NSLog(@"Valentine's Day =%@",valentinesDay);
}
return 0;
}
//打印信息：
Valentine's Day =2012-02-14 05:02:00 +0000
//格式化日期以便显示：
df.dateFormat=@"EEEE,MMMM d";
/**
*格式化日期例子
*/
#import
int main(int argc,const char *argv[]){
@autoreleasepool{
NSString *dateString=@"02/14/2012";
NSDateFormatter *df=[[NSDateFormatter alloc]init];
df.dateFormat=@"MM/dd/yyyy";
NSDate *valentinesDay=[df dateFromStrign:dateString];
NSLog(@"Unformatted Valentine's Day=%@",valentinesDay);
NSLog(@"Formatted Valendtine's Day=%@",[df stringFormDate:valentinesDay]);
}
return 0;
}
/**
*加减日期
*/
//NSDateComponents、NSCalendar NSDateComponents指定了时间长度
NSDateComponents *weekBeforeDateComponents=[[NSDateComponents alloc]init];
//减掉一周就将NSDateComponents中的week属性设为-1
weekBeforeDateComponents.week=-1;
NSDate *vDayShoppingDay=[[NSCalendar currentCalendar]
dateByAddingComponents:weekBeforeDateComponents toDate:valentinesDay options:0];
/**
*加减日期例子
*/
#import
int main(int argc,const char *arv[]){
@autoreleasepool{
NSString *dateString=@"02/14/2012";
NSDateFormat *df=[[NSDateFormatter alloc[init];
df.dateFormat =@"MM/dd/yyyy";
NSDate *valentineDay=[df dateFromString:dateString];
NSLog(@"valentines's Day=%@",valentinesDay);
NSDateComponents *weekBeforeDateComponents=[[NSDateComponents alloc]init];
weekBeforeDateComponents.week=-1;
NSDate *vDayShopingDay=[[NSCalendar currentCalendar] dateByAddingComponetns:weekBeforeDateComponents toDate:valentinesDay optioins:0];
NSLog(@"Shop for Valentine's Day by %@",vDayShoppingDay);
}
return 0;
}
/**
*使用定时器调度并重复执行任务
*/
//特定时间重复执行任务方式：NSTimer
//设置时间间隔：dateWithTimeIntervalSinceNow:10.0
NSDate *scheduledTime=[NSDate dateWithTimeINtervalSinceNow:10.0];
NSString *customUserObject=@"To demo userInfo";
NSTimer *timer=[[NSTimer alloc]initWithFireDate:scheduledTime
interval:2
target:self
selector:@selector(task)
userInfo:customUserObject
repeats:YES];
//参数说明：
参数一：日期对象指定了定时器何时变成活动状态。
参数二：接下来是间隔时间，是定时器再次发送消息前所需等待的秒数。
参数三：是目标参数描述符目标是方法所处的对象由于方法与定时器一样都位于月应用委托中，因此可以使用self关键字
参数四：selector参数是位于圆括号中的方法名前面是@selector关键字。
参数五：userInfo是定时器使用的自定义内容。可 |