c++ - 从 Objective-C 子对象调用 C++ 对象的方法

Question

我有一些 Objective-C++ 代码，我试图从 Objective-C 对象中获取事件以调用 C++ 对象中的方法。我是 Objective-C 的新手，所以我可能做错了。

例子:

@interface KnobClass {
}
-(void)Event;
@end

class DoorClass {
    public:
    KnobClass * knob;
    void start() { knob = [[KnobClass allocate] init]; }
};

class AlarmClass {
    public:
    void Alert();
};

class HouseClass {
    public:
    DoorClass door;
    AlarmClass alarm;
};

int main() {
    //...
    HouseClass house;
    house.door.start();
    //...
    return 0;
}

方法 [house.door.knob Event] 是在事件上生成的，我希望它能够调用 house.alarm.Alert()。但我很困惑如何以正确的方式完成这项工作。有人可以建议实现此目的的方法吗？

Answer 1

我也在学习 Objective-C。这适用于 gcc 4.3.3:

#import <Foundation/Foundation.h>

class AlarmClass {
    public:
    void Alert() {
        printf("Alert!\n");
    }
};    

@interface KnobClass: NSObject {
    AlarmClass *alarm;
}
-(void)Event;
-(id)initWithAlarm:(AlarmClass*) alarm;
@end

@implementation KnobClass: NSObject

-(id)initWithAlarm:(AlarmClass*) a
{
    self = [super init];
    alarm = a;
    return self;
}

-(void)Event
{
    alarm->Alert();
}
@end

class DoorClass {
    public:
    KnobClass * knob;
    void start(AlarmClass *a) {
        knob = [[KnobClass alloc] initWithAlarm: a];
    }

    void doEvent() {
        [knob Event];
    }
};

class HouseClass {
    public:
    DoorClass door;
    AlarmClass alarm;
};

int main(int argc, const char *argv[]) {
    //...
    HouseClass house;
    house.door.start(&house.alarm);
    house.door.doEvent();
    //...
    return 0;
}