X Macro goodness for removing duplication in NSCoder implementations

XSynthesizeCoders.h

typedef void (^XDecodeBlock)(id x);
typedef id (^XEncodeBlock)(void);

// posing a CLLocationCoordinate2D as a CGPoint because of a bug in NSValue valueWithMKCoordinate...
static XEncodeBlock XCLLocationCoordinate2DEncoder(CLLocationCoordinate2D loc)
{
    return ^{
        return [NSValue valueWithCGPoint:CGPointMake(loc.latitude, loc.longitude)];
    };
}

static XDecodeBlock XCLLocationCoordinate2DDecoder(CLLocationCoordinate2D * loc)
{
    return ^(NSValue * v){
        CGPoint p = [v CGPointValue]; loc->latitude = p.x; loc->longitude = p.y;
    };
}

-(void) encodeWithCoder: (NSCoder*) coder
{
#define X(xtype, xivar) [coder encode##xtype:xivar forKey:@#xivar];
#define XX(xivar, xencode, xdecode) do { XEncodeBlock x = xencode; [coder encodeObject:x() forKey:@#xivar]; } while (0);
    XEncodeIvars
#undef XX
#undef X
    
#ifdef XEncodeBlock
    XEncodeBlock
#endif
}

-(id) initWithCoder: (NSCoder*) decoder
{
#define X(xtype, xivar) xivar = [decoder decode##xtype##ForKey:@#xivar];
#define XX(xivar, xencode, xdecode) do { id x = [decoder decodeObjectForKey:@#xivar]; XDecodeBlock y = xdecode; y(x); } while (0);
    XEncodeIvars
#undef XX
#undef X
    
#ifdef XDecodeBlock
    XDecodeBlock
#endif
    
    return self;
}

ZFoo.h

@interface Foo : NSObject <NSCoder>

@property BOOL aBool;
@property BOOL anotherBool;
@property NSInteger anInteger;
@property NSInteger anotherInteger;
@property NSObject * anObject;
@property NSObject * anotherObject;
@property CLLocationCoordinate2D location;

@end

ZFoo.m

@implementation Foo

#define XEncodeIvars \
X(Bool, _aBool) \
X(Bool, _anotherBool) \
X(Integer, _anInteger) \
X(Integer, _anotherInteger) \
X(Object, _anObject) \
X(Object, _anotherObject) \
XX(_location, XCLLocationCoordinate2DEncoder(_location), XCLLocationCoordinate2DDecoder(&_location))

#include "XSynthesizeCoders.h"

@end