koobas.hobune.stream
Passing NSDictionary from obj-C to C#
I have a Unity app which needs to read data from an iOS library, and I created an interface.mm file to connect that library to Unity.
I set up a GetNumber function in the interface file which returns an int. I can successfully read the int in Unity using [DllImport ("__Internal")] private static extern int GetNumber();
Now all I need to do is pass a NSDictionary instead of an int, but objective-c is incredibly foreign to me and I haven't yet figured out how to make things work.
My current interface code is:
#include "KochavaUnitySupport.h"
extern "C" {
//Works!
int GetNumber()
{
return 3;
}
//Need Help
string GetPastboardAttribute(string pasteboardName)
{
UIPasteboard *pb = [UIPasteboard pasteboardWithName:pasteboardName create:NO];
if (pb) return pb.string;
}
//Need serious help
NSDictionary* GetKochavaInfo()
{
NSDictionary *kochavaInfo = [[KochavaUnitySupport sharedManager]returnKochavaInfo];
return kochavaInfo;
}
}
MANY thanks to anyone that knows what I need to change to make the above code work, and what datatype I should be expecting to receive the NSDictionary in Unity (a Hashtable would be perfect).
Received a tip from SuperPig on IRC that I should try implementing a visitor pattern - iterating through each element of the NSDictionary pointer and activating a c# callback function. Any other ideas, or tips on making this work?
Ok, I now have this code working perfectly: http://pastebin.com/P2wCkiWe Unfortunately, I'd rather not rely on iOS 5's builtin JSON library, so I am now working on some code to build the JSON string manually through string concatenation. Any suggestions?
Done! This code should be extremely useful to anyone that happens to encounter similar situations in the future:
#import "JSONKit.h"
char* AutonomousStringCopy (const char* string)
{
if (string == NULL)
return NULL;
char* res = (char*)malloc(strlen(string) + 1);
strcpy(res, string);
return res;
}
extern "C" {
char* GETDICTIONARY()
{
NSDictionary *myNSDict = //Get Dict Here
//Works great for iOS 5+
//NSError *error;
//NSData *jsonData = [NSJSONSerialization dataWithJSONObject:myNSDict options:0 error:&error];
//NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
//Much more compatible library
NSString *jsonString = [myNSDict JSONString];
const char* jsonChar = AutonomousStringCopy([jsonString UTF8String]);
return AutonomousStringCopy(jsonChar);
}
}
Ins$$anonymous$$d of implementing your own AutonomousStringCopy, why don't you use `strdub`?
Is there a reason you didn't use NSString's method for generating CStrings?
It's not possible for Unity to work directly with an NSDictionary, as far as I know, so what you need to do is have your C DLL access it on your behalf. I'd use something like a visitor pattern for this:
void GetKochavaInfo(void (*visitorFn)(const char* key, const char* value))
{
// Get your NSDictionary
for(NSString* key in dictionary)
{
NSObject* value = [dictionary objectForKey:key];
// do something with value to get a string out of it
visitorFn([key UTF8String], [valueStr UTF8String]);
}
}
On the C# side, you'd then declare a delegate type to describe the function pointer:
public delegate void DictionaryVisitorHandler(string key, string value);
and then the external function definition:
public extern void GetKochavaInfo(DictionaryVisitorHandler handler);
Good idea. I am currently leaning towards JSON serialization, but i'll keep your solution in $$anonymous$$d
I use https://developers.facebook.com/docs/unity/reference/current/Json/ on C# side to deserialize JSON in unity.
