将日期字符串转换为X月X日形式

得到的日期字符串为： 

2013-04-02 16:47:15

需要将其转换为 4月2日  的形式，实现如下：

// 根据时间来返回显示的时间字符串

- (NSString *)transformTime:(NSString *)timeStr
{
    if ([timeStr length]<11) {
        return timeStr;
    }
    NSDateFormatter *formater = [[ NSDateFormatter alloc] init];
    NSTimeZone *localzone = [NSTimeZone localTimeZone];
    [formater setTimeZone:localzone];
    [formater setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *modefiTime = [formater dateFromString:timeStr];    
    
    NSCalendar *gregorian = [[NSCalendar alloc]
                             initWithCalendarIdentifier:NSGregorianCalendar];    
    //设置日期里要获取的单元类型
    NSInteger flag = NSYearCalendarUnit |NSMonthCalendarUnit |NSDayCalendarUnit |NSHourCalendarUnit |NSMinuteCalendarUnit |NSSecondCalendarUnit;
    NSDateComponents* dc = [[[NSDateComponents alloc] init] autorelease];
    dc = [gregorian components:flag fromDate:modefiTime];
//    NSInteger nowHour = [dc hour];
//    NSInteger nowMin = [dc minute];
//    NSInteger nowYear = [dc year];
    NSInteger nowMonth = [dc month];
    NSInteger nowDay = [dc day];
    
    NSString *time = [NSString stringWithFormat:@"%d月%d日", nowMonth, nowDay];
    NSLog(@"time = %@", time);
    return time;
}