按月将NSArray与NSDate对象分类到NSDictionary中

Question

我正在构建一个UITableView并希望按月分组,以便我可以将这些字符串作为我的节标题,例如:

February 2013
- Item 1
- Item 2

January 2013
- Item 1
- Item 2

我有一个NSArray自定义对象,其pubDate属性是一个NSDate.

如何使用该NSDate对象将我的自定义对象NSDictionary按月分组？

Answer 1

像这样排序数组

NSArray *sortedArray = [yourArrayOfCustomObjects sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        NSDate *firstDate = [(YourCustomObject*)obj1 pubDate];
        NSDate *secondDate = [(YourCustomObject*)obj2 pubDate];
        return [firstDate compare:secondDate];        

    }];

//现在进行简单的迭代,您可以确定所有相同月份的条目.

//代码不完整仅用于说明目的.

//您还必须处理年度变化.

int curMonth = 0;
int prevMonth = 0;
foreach(CustomObject *obj in sortedArray)
{
   NSDateComponents *components = [[NSCalendar currentCalendar] components:NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:obj.pubDate];
   prevMonth = curMonth; 
   curMonth = components.month;
   if(prevMonth != 0 && curMonth != prevMonth)
   {
      //Month Changed
   }
}