ios - 编译器错误 - iOS "expected ")"before "问题

Question

下面的代码有什么问题？ Xcode 4 说带有“Question”的两个方法声明由于“Question”之前的“预期”)而无法编译；消息，如以下代码中的注释所示。Question 类编译并且此代码以前一直在工作。我对问题进行了一些更改，但将它们撤回以尝试找出此编译时错误。

#import <Foundation/Foundation.h>
#import "Question.h"

@interface AppState : NSObject {

    int chosenAnswer;
    int correctAnswers;
    int currentQuestionNumber;

    // this will contain the hash table of question objects
    NSMutableDictionary *questionHash;

}

@property (nonatomic) int chosenAnswer;
@property (nonatomic) int correctAnswers;
@property (nonatomic) int currentQuestionNumber;
@property (nonatomic, retain) NSDictionary *questionHash;

- (void)        printQuestions;
- (void)        printDescription;
- (void)        addQuestion: (Question *) question; // <==== error  
- (int)         numberOfQuestions;
- (void)        saveState; 
- (void)        resetState;
- (Question *)  currentQuestion; //  <=====   error


@end

这是问题.h:

#import <Foundation/Foundation.h>

#import "AppState.h"

@interface Question : NSObject {

    NSString    *questionTxt;
    int         correctAnswer;
    int         number;

    // this will contain the hash table of questions_answer objects
    NSMutableDictionary *answerHash;

}


@property (nonatomic, retain)   NSString * questionTxt;
@property (nonatomic) int       correctAnswer;
@property (nonatomic) int       number;
@property (nonatomic, retain)   NSMutableDictionary *answerHash;


 -(void)                            addAnswer: (NSString *) answer;   
- (NSMutableArray *)                answerArray;
- (void)                printDescription; 
- (void)                printAnswers;
- (NSString *)          correctAnswerText;
- (Question *)                      currentQuestion;

@end

Answer 1

循环依赖？ AppState 正在导入 Question，而 Question 正在导入 AppState。

转发声明其中之一以打破循环，例如在你的 AppState @interface 语句之前使用 @class Question，就像这样

@class Question;

@interface AppState : NSObject {

    int chosenAnswer;
    int correctAnswers;
    int currentQuestionNumber;

   // this will contain the hash table of question objects
   NSMutableDictionary *questionHash;
}
...

相关问题:@class vs. #import