＆＃39;期待一种类型＆＃39;使用Parse的Obj-C中的错误

Question

我正在为我的程序声明三个相关的类，并获得大量“预期类型”和“未知类型名称”错误。看了StackOverflow上的类似问题后，我想也许我遇到了循环依赖的问题，但我似乎无法通过使用@class前向声明来解决错误。我需要做些什么来构建这个项目？

BQUser.h

#import <Parse/Parse.h>
#import "BQQuestion.h"
#import "BQAnswer.h"

@interface BQUser : PFUser<PFSubclassing>

@property (retain) NSString *userDescription;
@property (retain) PFFile *userImage;

- (BQQuestion *) addNewQuestion:(NSString *) question; //expected a type
- (BQAnswer *) addNewAnswer:(NSString *) answer toQuestion:(BQQuestion *)     question; //expected a type
- (void) likeAnswer: (BQAnswer *) answer; //expected a type

@end

BQQuestion.h

#import <Parse/Parse.h>
#import "BQUser.h"

@interface BQQuestion : PFObject<PFSubclassing>

@property (retain) BQUser *user; //unknown type name 'BQUser'; did you mean 'PFUser'?
@property (retain) NSString *questionText;
@property (retain) NSArray *answers;
@property int answerCount;

+ (NSString *)parseClassName;

@end

BQAnswer.h

#import <Parse/Parse.h>
#import "BQUser.h"
#import "BQQuestion.h"

@interface BQAnswer : PFObject<PFSubclassing>

@property (retain) BQUser *user; //unknown type 'BQUser'; did you mean 'PFUser'?
@property (retain) BQQuestion *question; //unknown type name 'BQQuestion'
@property (retain) NSString *answerText;
@property int votes;

+ (NSString *)parseClassName;

@end