从C ++对象调用Objective-C父对象 [英] Calling Objective-C parent from C++ object
问题描述
在iOS上创建音频单元扩展需要混合C ++和Objective-C类.结果,我现在有了一个带有C ++对象作为其变量之一的Objective-C对象.
Creating Audio Unit Extensions on iOS requires mixing of C++ and Objective-C classes. As a result I now have an Objective-C object with a C++ object as one of its variables.
我希望C ++子对象能够将某些状态更改通知其Objective-C父/所有者.
I would like the C++ child object to be able to notify its Objective-C parent/owner of certain state changes.
使用伪代码:
void cppChildObject::callMom() {
objectiveCParent::notificationMethod();
}
这是否可以优雅地做到?
Is this possible in an elegant way?
推荐答案
这取决于您如何定义优雅...如果C ++类位于Objective-C ++文件中(一个带有.mm扩展名),并且不在Objective-C ++源文件中的C ++代码直接使用.问题是C ++代码只有在Objective-C ++源文件中才可以使用Objective-C类型.这是一个简单的示例,希望对您有所帮助.
It depends on how you define elegant... This is possible in a fairly elegant way if the C++ class is in an Objective-C++ file (one with the .mm extension) and is not used directly by C++ code that is not in an Objective-C++ source file. The problem is that C++ code can use Objective-C types only if it is in an Objective-C++ source file. Here is a quick example, hopefully you will find it helpful.
Objective-C ++文件,mylib.mm
(请注意.mm扩展名):
Objective-C++ file, mylib.mm
(note the .mm extension):
#import "objcpp.h"
#import <stdio.h>
#import "cpp.h"
// A C++ class in an Objective-C++ file.
// This C++ class would not need to sub-class ParentNotifier, and ParentNotifier
// would not be needed at all if it were not for OutsiderCPP, which talks to its
// Objective-C parent through InsiderCPP.
class InsiderCPP : public ParentNotifie {
public:
InsiderCPP(MyClassOCPP * parent) : myParent(parent){}
void doSomething() {
callMom("To Mom from insider.");
}
void callMom(const char * msg) {
[myParent notificationMethod:msg];
}
private:
MyClassOCPP * __weak myParent;
};
@interface MyClassOCPP ()
@property InsiderCPP * insiderChild;
@property OutsiderCPP * outsiderChild;
@end
@implementation MyClassOCPP
-(id)init {
self.insiderChild = new InsiderCPP(self);
self.outsiderChild = new OutsiderCPP(self.insiderChild);
return self;
}
-(void)doWork {
self.insiderChild->doSomething();
self.outsiderChild->doSomething();
}
-(void)notificationMethod:(const char *)msg {
printf("Parent has been notified with: %s\n", msg);
}
-(void)dealloc {
delete self.insiderChild;
delete self.outsiderChild;
}
@end
以下是相应的标题objcpp.h
:
#ifndef objcpp_h
#define objcpp_h
#import <Foundation/Foundation.h>
@interface MyClassOCPP : NSObject
-(id)init;
-(void)dealloc;
-(void)doWork;
-(void)notificationMethod:(const char*)msg;
@end
#endif
这是一个与Objective-C无关的纯" C ++源文件(mylib.cpp
):
Here is a "pure" C++ source file (mylib.cpp
) having nothing to do with Objective-C:
#include <stdio.h>
#include "cpp.h"
void OutsiderCPP::callMom(const char * m) {
myParent->callMom(m);
}
void OutsiderCPP::doSomething() {
callMom("To Mom from outsider.");
}
,这是对应的标题(cpp.h
):
and here is the corresponding header (cpp.h
):
#ifndef cpp_h
#define cpp_h
class ParentNotifier
{
public:
virtual void callMom(const char *) = 0;
};
class OutsiderCPP
{
public:
OutsiderCPP(ParentNotifier * p) : myParent(p) {}
void doSomething();
void callMom(const char *);
private:
ParentNotifier * myParent;
};
#endif
请注意,此示例仅用于说明目的,并非生产质量.
Please note that this example is for illustration purposes only and is not production quality.
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