Objective C, Linking Error with extern variable..
- by LCYSoft
I have a very simple java code like this. I don't have any idea how to do this in Objective C. Especially, the static part which calls the getLocalAddress() method and assign it into the static string variable. I know how to set a static variable and a static method in Objective but I dont know how to implement that static { } part in java.
Thanks in advance...
public class Address {
public static String localIpAddress;
static {
localIpAddress = getLocalIpAddress();
}
public Address() {
}
static String getLocalIpAddress() {
//do something to get local ip address
}
}
I added this in my .h file
#import <Foundation/Foundation.h>
extern NSString *localIpAddress;
@class WifiAddrss;
@interface Address : NSObject {
}
@end
And my .m file looks like
#import "Address.h"
#import "WifiAddress.h"
@implementation Address
+(void)initialize{
if(self == [Address class]){
localIpAddress = [self getLocalIpAddress];
}
}
+(NSString *)getLocalIpAddress{
return address here
}
-(id)init{
self = [super init];
if (self == nil){
NSLog(@"init error");
}
return self;
}
@end
And Now I am getting a linking error and it complains about "extern NSString *localIpAddress" part. If I change the extern to static, it works fine. But what I wanted to do is that I want make the scope of "localIpAddress" variable as grobal. Since if I put "static" in front of a variable in Objective-C then the variable is only visible in the class. But this time, I want to make that as a grobal variable. So my question is how to make "localIpAddress" variable as a grobal variable which is initialized once when the first time Address class is created.. Thanks in advance...
