ios xcode 4.6 中的“实例消息的接收器类型是前向声明”
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/15719681/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
"Receiver type for instance messages is a forward declaration" in xcode 4.6
提问by Willen
I want to call c++ class in my ViewController. So I create a class like this: Hello.h
我想在我的 ViewController 中调用 c++ 类。所以我创建了一个这样的类：Hello.h
#import <Foundation/Foundation.h>
@interface Hello : NSObject{
class NewHello{
private:int greeting_text;
public:
NewHello(){
greeting_text=5;
}
void say_hello(){
printf("Greeting_Text = %d",greeting_text);
}
};
NewHello *hello;
}
-(void)sayHellooooo;
@end
Hello.mm
你好.mm
#import "Hello.h"
@implementation Hello
-(void)sayHellooooo{
hello = new NewHello();
hello->say_hello();
}
@end
ViewController.h
视图控制器.h
#import <UIKit/UIKit.h>
//#include "Hello.h"
@class Hello;
@interface ViewController : UIViewController{
}
@end
ViewController.m
视图控制器.m
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(@"dddddddd");
Hello *aa = [[Hello alloc]init];
[aa sayHellooooo];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}
@end
It works fine in the project:http://files.cnblogs.com/cpcpc/Objective-C%E8%B0%83%E7%94%A8C.rar
在项目中运行正常：http: //files.cnblogs.com/cpcpc/Objective-C%E8%B0%83%E7%94%A8C.rar
But when I copy the code to my project,it appears "Receiver type for instance messages is a forward declaration" error.
但是当我将代码复制到我的项目时，出现“实例消息的接收器类型是前向声明”错误。
If I change "@class Hello;" to #import "Hello.h",it appears "Unkwon type class,did you mean Class" error in "class NewHello".
如果我改变“@class Hello;” 到#import“Hello.h”，在“class NewHello”中出现“Unkwon type class,did you mean Class”错误。
I use xcode 4.6.Can anybody help me?Thank you!
我使用 xcode 4.6。有人可以帮助我吗？谢谢！
回答by Mar0ux
The problem is (as you've stated) file type for ViewController.m is Obj-C and Hello.h is a Obj-C++ file. The solution is to add
问题是（如您所说） ViewController.m 的文件类型是 Obj-C 而 Hello.h 是 Obj-C++ 文件。解决方法是添加
#import "Hello.h"
to your ViewController.m file and change the file type of ViewController.m to Obj-C++ (from the right panel)
到您的 ViewController.m 文件并将 ViewController.m 的文件类型更改为 Obj-C++（从右侧面板）
