目标C圆形进口

Question

我具有被这样

SingletonClassA.h

@interface SingletonClassA : NSObject 

+ (SingletonClassA*) sharedInstance; 

@end 

SingletonClassA.m

#import "SingletonClassA.h" 
#import "SingletonClassB.h"  

@implementation SingletonClassA 

+ (SingletonClassA*) sharedInstance{ 
    static SingletonClassA* instance = nil; 

    static dispatch_once_t onceToken; 
    dispatch_once(&onceToken, ^{ 
     instance = [SingletonClassA]; 
     [[SingletonClassB shareInstance] methodB]; 
    }); 

    return instance; 
} 

@end 

SingletonClassB.h

定义了两个单实例类

@interface SingletonClassB : NSObject 

+ (SingletonClassB*) sharedInstance; 

@end 

SingletonClassB.m

#import "SingletonClassB.h" 
#import "SingletonClassA.h" 

@implementation SingletonClassB 

+ (SingletonClassB*) sharedInstance{ 
    static SingletonClassB* instance = nil; 

    static dispatch_once_t onceToken; 
    dispatch_once(&onceToken, ^{ 
     instance = [SingletonClassB]; 
     [[SingletonClassA shareInstance] methodA]; 
    }); 

    return instance; 
} 

@end 

当我生成项目，一切似乎是不错的，但是当我在模拟器或我的手机上运行，​​应用程序未启动并显示NSZombie错误。

Class _NSZombie_BSXPCMessage is implemented in both ?? and ??. 
One of the two will be used. Which one is undefined 

我试图删除应用程序，清理项目并再次运行..相同的错误。 当我在两个类中的一个中删除导入时，它工作正常。

你知道我做错了什么吗？

谢谢，

Answer 1

无法重现您的问题。

SingletonClassA.h

@interface SingletonClassA : NSObject 

+ (SingletonClassA *) sharedInstance; 
-(void)methodA; 

@end 

SingletonClassA.m

#import "SingletonClassA.h" 
#import "SingletonClassB.h" 

@implementation SingletonClassA 

+ (SingletonClassA*) sharedInstance{ 
    static SingletonClassA* instance = nil; 

    static dispatch_once_t onceToken; 
    dispatch_once(&onceToken, ^{ 
     instance = [SingletonClassA new]; 
     [[SingletonClassB sharedInstance] methodB]; 
    }); 

    return instance; 
} 

@end 

SingletonClassB.h

@interface SingletonClassB : NSObject 

+ (SingletonClassB *) sharedInstance; 

-(void)methodB; 

@end 

SingletonClassB.m

#import "SingletonClassB.h" 
#import "SingletonClassA.h" 

@implementation SingletonClassB 

+ (SingletonClassB*) sharedInstance{ 
    static SingletonClassB* instance = nil; 

    static dispatch_once_t onceToken; 
    dispatch_once(&onceToken, ^{ 
     instance = [SingletonClassB new]; 
     [[SingletonClassA sharedInstance] methodA]; 
    }); 

    return instance; 
} 

@end 

在.m文件导入类不应该引入进口周期。您没有使用new或alloc init。这是为什么？