iphone memset问题

Question

我在我的头文件中定义了一个结构：

#import <UIKit/UIKit.h>    
typedef struct ORIGINAL_QUOTA_DATA_tag
{
    byte    exch;          
    byte    complex_stat;                   
    char    contract[8];    
    byte    status;         
    byte    type;        
}ORIGINAL_QUOTA_DATA;
@interface NetTestAppDelegate : NSObject <UIApplicationDelegate> {
    CFSocketRef _socket;
    CFDataRef address;
    ORIGINAL_QUOTA_DATA oQuota;
}
@property (nonatomic, retain) IBOutlet UIWindow *window;

在.m文件中：

    static void TCPServerConnectCallBack(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info){
memset(&oQuota, 0, sizeof(oQuota));
}

但它得到了worning：

​

Answer 1

您正在从C函数引用oQuota (它也是静态的，但这不是问题所在)。您的oQuota变量只在您的NetTestAppDelegate的Objective-C方法实现的“作用域”内

void myCFunction()
{
    // oQuota cannot be referenced here.
}

@implementation NetTestAppDelegate
- (void)myObjectiveCMethod
{
   // oQuota is in scope, can reference it.
}
@end

但是你能做的就是把对象传递给你的回调函数：

static void TCPServerConnectCallBack(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info){
    memset(
      &((NetTestAppDelegate *)info)->oQuota,
      0,
      sizeof(((NetTestAppDelegate *)info)->oQuota)
    );
    // Not sure whether the sizeof works, try it.
}

在你的CFSocketContext中，你需要设置：

myCFSocketContext.info = self;