NSDate和NSString

+(NSDate*) convertDateFromString:(NSString*)uiDate

{

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

    [formatter setDateFormat:@"yyyy年MM月dd日"];

    NSDate *date=[formatter dateFromString:uiDate];

    return date;

}



 



输入的日期字符串形如：@"2012-07-30 13:08:08"



- (NSDate *)dateFromString:(NSString *)dateString{



NSDateFormatter *dateFormatter = [[NSDateFormatteralloc] init];



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



NSDate *destDate= [dateFormatter dateFromString:dateString];



[dateFormatter release];



return destDate;



}



 



- (NSString *)stringFromDate:(NSDate *)date{



NSDateFormatter *dateFormatter = [[NSDateFormatteralloc] init]; 



//zzz表示时区，zzz可以删除，这样返回的日期字符将不包含时区信息。



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



NSString *destDateString = [dateFormatter stringFromDate:date];



[dateFormatter release];



return destDateString;



}



 //从起始日期经过一定天数后/前（day为负数）的日期

- (NSString *)dateStringFromDate:(NSDate *)date afterDay:(int)day

{

    NSCalendar *calendar = [NSCalendar currentCalendar];

    NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];

    //这边填入需要增加的天数

    [componentsToAdd setDay:day];

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

    [dateFormatter setDateFormat:@"yyyy-MM-dd"];

    NSDate *fromDate=date;

    NSDate *dateAfterDay = [calendar dateByAddingComponents:componentsToAdd toDate:fromDate options:0];

    [componentsToAdd release];

    NSString *dateStr = [dateFormatter stringFromDate:dateAfterDay];

    [dateFormatter release];

    

    return dateStr;

}