NSDate 的一些操作（比較、創建、在現有date加減一定時間等）

創建當前時間

 

NSDate *date = [NSDate date];

 

 

從現在開始的24小時

        NSTimeInterval a_day = 24*60*60;

        NSDate *tomorrow = [NSDate dateWithTimeIntervalSinceNow:a_day];

根據已有日期創建日期

 

NSTimeInterval a_day = 24*60*60;
NSDate *date = [NSDate date];
NSDate *tomorrow = [date addTimeInterval: date];

 

日期比較

 

      BOOL isEqual = [date isEqualToDate:tomorrow];
f(isEqual){
NSLog(@"equal");

 

//獲取較早的日期

 

NSDate *earlier_date = [tomorrow earlierDate:date];
  NSLog(@"earlierDate  = %@",earlierDate);

 

//較晚的日期

 

NSDate *laterDate = [tomorrow laterDate:date];
NSLog(@"laterDate  = %@",laterDate);

 

//兩個日期之間相隔多少秒

 

NSTimeInterval secondsInterval= [date timeIntervalSinceDate:tomorrow];
NSLog(@"secondsInterval=  %lf",secondsInterval);

 

 

 //通過NSCalendar類來創建日期

 

 

NSDateComponents *comps = [[NSDateComponentsalloc]init];
[comps setMonth:01];
[comps setDay:31];
[comps setYear:2013];
NSCalendar *calendar = [[NSCalendaralloc]initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *date = [calendar dateFromComponents:comps];

 

 //從已有日期獲取日期

 

unsigned units  = NSMonthCalendarUnit|NSDayCalendarUnit|NSYearCalendarUnit;
NSDateComponents *_comps = [calendar components:units fromDate:date];
NSInteger month = [_comps month];
NSInteger year = [_comps year];
NSInteger day = [_comps day];
//NSDateFormatter實現日期的輸出
NSDateFormatter *formatter = [[NSDateFormatteralloc]init];
[formatter setDateStyle:NSDateFormatterFullStyle];//直接輸出的話是機器碼
//或者是手動設置樣式[formatter setDateFormat:@"yyyy-mm-dd"];
NSString *dateString = [formatter stringFromDate:date];
NSLog(@"dateString = %@",dateString);
NSLog(@"formater = %@",formatter);

 

//獲取日期格式對象

 

- (NSDateFormatter *)getDateFormatter {
    if (dateFormatter == nil) {
    dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateStyle:NSDateFormatterMediumStyle];
    [dateFormatter setTimeStyle:NSDateFormatterNoStyle];
    }
    return dateFormatter;
}