NSInvalidArgumentException'，原因：'謂詞的未知謂詞類型：BLOCKPREDICATE（0x70ad750）'錯誤

Question

我有一個核心數據庫，我嘗試使用塊謂詞創建一個抓取請求，但是我得到一個Unknown Predicate錯誤：

NOTE: employeeToHouse is a property of type House that was created for me when I subclassed NSManagedObject

NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Place"]; 
request.predicate  = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) { 
    Place *sortPlace   = (Place *)evaluatedObject; 
    CLLocation *placeLocation = [[CLLocation alloc] initWithLatitude:sortPlace.latitude.doubleValue 
                  longitude:sortPlace.longitude.doubleValue]; 
    CLLocationDistance distance = [placeLocation distanceFromLocation:self.userLocation]; 
    sortPlace.distanceToUser = [NSNumber numberWithDouble:distance]; 
    if(distance<3000) 
    { 
     return YES; 
    } 
    return NO; 
}]; 
request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@ "distanceToUser" 
                       ascending:YES 
                        selector:@selector(localizedCaseInsensitiveCompare:)]]; 

[self.loadingView removeSpinner]; 
[self setupFetchedResultsControllerWithFetchRequest:request]; 

然後我得到這個錯誤：

NSInvalidArgumentException', reason: 'Unknown predicate type for predicate: BLOCKPREDICATE(0x70ad750)'

難道我做錯了什麼？

Answer 1

AFAIK您不能在CoreData中使用塊謂詞。

查看頂級投答案在這裏：NSFetchRequest and predicateWithBlock

原因是，CoreData不能轉換包含在一個塊到一個SQL查詢的C代碼。