iPhone OS 3.x - background asyncsockets (if statement is not workable?)

Question

I am trying to implement the background mode with async socket. The following are a few codes:

CFReadStreamRef theReadStream;
CFWriteStreamRef theWriteStream;

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0) {        
    CFReadStreamSetProperty (theReadStream,  kCFStreamNetworkServiceType, kCFStreamNetworkServiceTypeVoIP);
    CFWriteStreamSetProperty(theWriteStream, kCFStreamNetworkServiceType, kCFStreamNetworkServiceTypeVoIP); 
}

I know kCFStreamNetworkServiceType and kCFStreamNetworkServiceTypeVoIP are available in iPhone with iOS started at 4.0.

The above codes were workable indeed when I built into iPhone with iOS started at 4.0.

However, I could not build the above codes into iPhone with iOS 3.1 successfully.

I have added the statement, ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0), to the above codes.

I don't know why I could not enter the program at all especially I have added the if statement.

You are not able to build. So what error you are getting when you build ? — Darshan Prajapati, Jul 30 '12 at 04:10
It showed black screen only in runtime after I built into iPhone with iOS 3.1. Then, I got the error such as: dyld: Symbol not found: _kCFStreamNetworkServiceType — Chih-Shu Shih, Jul 30 '12 at 06:24
I have also used the statement, `#if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_4_0`, and it still did not work. — Chih-Shu Shih, Jul 31 '12 at 07:07
Because `kCFStreamNetworkServiceType` and `kCFStreamNetworkServiceTypeVoIP` belong to constant, I also can not use `instancesRespondToSelector` to avoid it. — Chih-Shu Shih, Jul 31 '12 at 07:11
Telll me how you used that #if statement. Write the code snippet here. — Darshan Prajapati, Aug 03 '12 at 04:16

score 0 · Answer 1 · answered Jul 30 '12 at 04:15

I think you are getting compile time error because you are using kCFStreamNetworkServiceType and kCFStreamNetworkServiceTypeVoIP in your code which is not available in iOS 3.1. Its available in iOS 4.0 onwards. So you should use #if kind of macros to get rid of that error. Hope that helps to you.

iPhone OS 3.x - background asyncsockets (if statement is not workable?)

1 Answers1