Google protocol buffers on iOS

Question

Is the metasyntactic static library for iOS . . .

http://code.google.com/p/metasyntactic/wiki/ProtocolBuffers

. . . compatible with regular old C++ compiled

Answer 1

EDIT : I had answered this earlier but was deleted by moderator. So I have included some code from the tutorial.

A tutorial which is almost same as the answer posted above - Using Google Protocol Buffers in Objective-C on iOS and the Mac

Follow the steps given in learnvst's answer, and refer the comments for pitfalls. I followed the exact same steps except for

add the directory of google headers to your additional include directories I added the src/ directory in the header search paths, instead of the google directory.

Also, when i did #import xyz.pb.h the project wasn't building. When I renamed my .m file to .mm i was able to build. This point is mentioned in the tutorial very subtly :P.

Basically, any .m file which is importing a any .pb.h file, should be renamed with extension .mm

Here's some content from the tutorial -

PROTO FILE

package kotancode;

enum ZombieType {
    SLOW = 0;
    FAST = 1;
}

message ZombieSighting {
    required string name = 1;
    required double longitude = 2;
    required double latitude = 3;
    optional string description = 4;
    required ZombieType zombieType = 5 [default = SLOW];
}

ZombieSightingMessage.h

// -- ZombieSightingMessage.h - note my C++ object is not in the public interface.
#import 

@interface ZombieSightingMessage : NSObject
- (void)doSomething;
@end

ZombieSightingMessage.mm

// -- ZombieSightingMessage.mm
#import 
#import "ZombieSightingMessage.h"
#import "zombie.pb.h"

@implementation ZombieSightingMessage

- (void)doSomething {
    // Doing random stuff with a UIView here to show the mixing
    // of C++ and Objective-C/Cocoa syntax in the same file...
    UIView *uiView = [[UIView alloc] init];
    [uiView setCenter:CGPointMake(20, 10)];

    // instantiate my protobuf-generated C++ class.
    kotancode::ZombieSighting *zombieSighting = new kotancode::ZombieSighting();
    zombieSighting->set_name("Kevin");
    zombieSighting->set_description("This is a zombie");
    zombieSighting->set_latitude(41.007);
    zombieSighting->set_longitude(21.007);
    zombieSighting->set_zombietype(kotancode::ZombieType::FAST);

    // Some small tomfoolery required to go from C++ std::string to NSString.
    std::string x = zombieSighting->DebugString();
    NSString *output = [NSString stringWithCString:x.c_str() encoding:[NSString defaultCStringEncoding]];
    NSLog(@"zombie: %@", output);

    // Instantiate another zombie from the previous zombie's raw bytes.
    NSData *rawZombie = [self getDataForZombie:zombieSighting];
    kotancode::ZombieSighting *otherZombie = [self getZombieFromData:rawZombie];

    // Dump the second zombie so we can see they match identically...
    NSString *newOutput = [NSString stringWithCString:otherZombie->DebugString().c_str() encoding:[NSString defaultCStringEncoding]];
    NSLog(@"other zombie: %@", newOutput);

    // Grimace all you want, but this is C++ and we need to clean up after ourselves.
    free(zombieSighting);
    free(otherZombie);

}

// Serialize to NSData. Note this is convenient because
// we can write NSData to things like sockets...
- (NSData *)getDataForZombie:(kotancode::ZombieSighting *)zombie {
    std::string ps = zombie->SerializeAsString();
    return [NSData dataWithBytes:ps.c_str() length:ps.size()];
}

// De-serialize a zombie from an NSData object.
- (kotancode::ZombieSighting *)getZombieFromData:(NSData *)data {
    int len = [data length];
    char raw[len];
    kotancode::ZombieSighting *zombie = new kotancode::ZombieSighting;
    [data getBytes:raw length:len];
    zombie->ParseFromArray(raw, len);
    return zombie;
}

@end

EDIT : I am using Xcode 4.5. Even after I followed all the steps I was getting a linker error.

symbols not found for architecture i386

Due to this I couldnt run the code on simulator. But it worked on actual device