如何使用NSSortDescriptor对NSMutableArray进行排序？(How to sort a NSMutableArray using NSSortDescriptor?)

 我正在从JSON webservice解析数据，然后使用以下代码按价格，日期，折扣等对数据进行排序。 
 
 这是我用来对数据进行排序的代码： 
 
-(void)priceSort:(id)sender {

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc]
                                     initWithKey: @"price" ascending: YES];

NSMutableArray *sortedArray = (NSMutableArray *)[self.displayItems
                                          sortedArrayUsingDescriptors: [NSArray arrayWithObject:sortDescriptor]];

[self setDisplayItems:sortedArray];

[self.tableView reloadData];


}
 
 当我尝试按价格排序时，这种方法很好，但是当我想按照评论数排序时，我似乎无法正确地获取代码： 
 
 我用的价格： 
 
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc]
                                         initWithKey: @"price" ascending: YES];
 
 但对于评论，我想得到“n”值。 看看它是如何嵌套在输出中的（显示项目mutableArray如下： 
 
"old_price" = 24;
        price = "9.9";
        reviews =         {
            **n = 11;**
            val = 70;
        };
        "sold_count" = 101;
 
 谢谢你对此有任何帮助:) 

I'm parsing data from JSON webservice and then using the following code to sort the data by price, date, discount etc.
 
here's the code I'm using to sort the data:
 
-(void)priceSort:(id)sender {

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc]
                                     initWithKey: @"price" ascending: YES];

NSMutableArray *sortedArray = (NSMutableArray *)[self.displayItems
                                          sortedArrayUsingDescriptors: [NSArray arrayWithObject:sortDescriptor]];

[self setDisplayItems:sortedArray];

[self.tableView reloadData];


}
 
this works fine when I'm trying to sort by price, however when I want to sort by number of reviews I can't seem to get the code right:
 
for price I use: 
 
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc]
                                         initWithKey: @"price" ascending: YES];
 
but for reviews I want to get the "n" value. see how it's nested in the output (of the display Items mutableArray below:
 
"old_price" = 24;
        price = "9.9";
        reviews =         {
            **n = 11;**
            val = 70;
        };
        "sold_count" = 101;
 
thanks for any help on this :)

原文：https://stackoverflow.com/questions/15027377