Ios NSPRedicate UNDEFINEDKEY的值

我有一个ProductData数组，如下所示，我想根据它们的类别对它们进行过滤，我应用了以下谓词，但它返回了错误

pTempElements =[[NSMutableArray alloc] initWithArray: [self.pElements filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"category = %@", @"4"]]];

由于未捕获异常“NSUnknownKeyException”而终止应用程序， 原因：'[valueForUndefinedKey:]：此类 不符合密钥类别的密钥值编码。'

这是佩利昂的俯瞰图

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您应该提供用于过滤数组的对象的属性名称。在这里，我想这是pCategory。你应该重写你的代码如下

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Ptemplements=[[NSMutableArray alloc]initWithArray:[self.pElements filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@PCCategory==%@，@4]]

你能试试这个吗？Ptemplements=[[NSMutableArray alloc]initWithArray:[self.pElements filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@PCCategory==%@，@4]]；是的，效果很好。

po self.pElements
<__NSArrayM 0x174241e30>(
<ProductData: 0x17427ce00>,
<ProductData: 0x17427cd80>,
<ProductData: 0x17427ce40>,
<ProductData: 0x17427ce80>,
)

#import "ProductData.h"

@implementation ProductData
@synthesize pId, pImage, pPrice, pName, pCategory

-(id)initWithDictionary:(NSDictionary *)aDict{
    self = [self init];
    if (self){
        self.pId = [aDict objectForKey:@"id"];
        self.pPrice = [aDict objectForKey:@"price"];
        self.pImage = [aDict objectForKey:@"imagePath"];
        self.pCategory = [aDict objectForKey:@"category"];
        self.pName = [aDict objectForKey:@"name"];
    }
    return self;
}