ios - NSPRedicate valueForUndefinedKey

Question

我有一个 ProductData 数组，如下所示，我想根据它们的 category 过滤它们，我应用了以下 Predicate，但它返回错误。

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

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ valueForUndefinedKey:]: this class is not key value coding-compliant for the key category.'

这里忽略了 pElements

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

ProductData.m

#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;
}

Answer 1

您应该给出您计划用来过滤数组的对象的属性名称。这里我猜是pCategory。您应该按如下方式重写代码

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