Objective c FilteredarrayingPredicate始终返回nil NSArray？

我使用CoreData获取了一些项目，我想使用filteredArrayUsingPredicate过滤这些结果，这给了我一些问题

CoreData获取：

NSFetchRequest *request = [[NSFetchRequest alloc]init];
[request setEntity:[NSEntityDescription entityForName:@"Collection" inManagedObjectContext:aContext]];
NSPredicate *pred = [NSPredicate predicateWithFormat:@"CategoryName==%@", aCategoryName];
[request setPredicate:pred];

NSError *error=nil;
NSArray *tempArray=[aContext executeFetchRequest:request error:&error];
[request release], request = nil;

NSLog(@"results: %@", tempArray);

这给了我这个结果：

results: (
    "<Collection: 0x8eb1920> (entity: Collection; id: 0x8eb0aa0 <x-coredata://7C4A4A5D-691A-4F02-9450-D0D910B53903/Collection/p95> ; data: {\n    CategoryID = 22832;\n    CategoryName = \"2000 - NOURISON 2000\";\n    IsDeleted = 0;\n    ManufacturerID = 192;\n    ModifiedOn = \"2012-03-08 09:00:46 +0000\";\n    ParentCategoryID = 0;\n    PhotoName = \"\";\n    SortOrder = 0;\n})"
)

result: (null) 

这给了我这个结果：

results: (
    "<Collection: 0x8eb1920> (entity: Collection; id: 0x8eb0aa0 <x-coredata://7C4A4A5D-691A-4F02-9450-D0D910B53903/Collection/p95> ; data: {\n    CategoryID = 22832;\n    CategoryName = \"2000 - NOURISON 2000\";\n    IsDeleted = 0;\n    ManufacturerID = 192;\n    ModifiedOn = \"2012-03-08 09:00:46 +0000\";\n    ParentCategoryID = 0;\n    PhotoName = \"\";\n    SortOrder = 0;\n})"
)

result: (null) 

---

不确定这里缺少了什么，我正在为这个过滤数组谓词传递正确的ManufacturerID of 192。

什么是ManufacturerID

通过使用

%@

格式说明符，它很可能是

[NSNumber numberwhithint:192]

或者，如果不想用

NSNumber

换行，可以将谓词中的格式从

%@

更改为

%d

NSInteger aManufacturerID = 192;

Collection *collection = [[tempArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"ManufacturerID==%d", aManufacturerID]]  lastObject];
NSLog(@"result: %@ " , collection);

---

什么是

amufacturerid

？很可能是

[NSNumber numberWithInt:192]

很奇怪，就是这样-我说奇怪是因为我之前在CoreData获取请求中过滤了这两个参数，并且我不需要将制造商强制转换为NSNumber。我应该试着用那篇文章作为答案，这样我就可以相信你了。