How to handle NSData as a #property - objective-c

Question

I'm trying to get a #property to work with NSData so that it becomes available to all methods in the class.
I've set up a little test project to help me debug the problem.
In my main.m is
FxPlug *data = [[FxPlug alloc] init];
[FxPlug makeCube];
NSLog (#"%#",[FxPlug.cubeData]);
and in the Class FxPlug.h is
#import <Foundation/Foundation.h>
#interface FxPlug : NSObject
#property NSData *cubeData;
+(void) makeCube;
#end
and FxPlug.m is
#import "FxPlug.h"
#implementation FxPlug
+ (void) makeCube; {
NSString *filePath = #"/Development/testNSDataProperty/test_cube_data.dat";
NSData *cubeData = [[NSData alloc] initWithContentsOfFile:filePath];
}
#end
So this is just a test to see if I can set the #property NSData *cubeData; in class FxPlug to the contents of a file and to see if it is passed back into the main.m class to NSLog out to the terminal.
I'd be really really appreciative of some help.
Basically, I'm trying to pass an NSData object between classes.
Many thanks!
Because my main project is an FxPlug, which is basically just one big class with a load of methods that are named specifically for the host app. So I need to add a new class method to that existing class to handle the NSData object. Or at least that's how I think it works!

Answer 1

If you want to use a property then you have to use and create a class instance and avoid using class methods, so:
FxPlug.h:
#import <Foundation/Foundation.h>
#interface FxPlug : NSObject
#property NSData *cubeData;
-(void) makeCube;
#end
FxPlug.m:
#import "FxPlug.h"
#implementation FxPlug
- (void) makeCube {
NSString *filePath = #"/Development/testNSDataProperty/test_cube_data.dat";
self.cubeData = [[NSData alloc] initWithContentsOfFile:filePath];
}
#end
main.m:
FxPlug *data = [[FxPlug alloc] init];
[data makeCube];
NSLog (#"%#", data.cubeData);
It can be done with class methods, and class-level variables, but not with #propertys. One halfway house is to use the singleton pattern where you only allow one instance of the class to exist at any one time.
EDIT: If you want to do it as a static class (not recommended), the code is below:
FxPlug.h:
#import <Foundation/Foundation.h>
#interface FxPlug : NSObject
+ (NSData *)cubeData;
+ (void)setCubeData:(NSData *)cubeData;
+ (void) makeCube;
#end
FxPlug.m:
#import "FxPlug.h"
static NSData *_cubeData = nil;
#implementation FxPlug
+ (NSData *)cubeData
{
return _cubeData;
}
+ (void)setCubeData:(NSData *)cubeData
{
_cubeData = cubeData;
}
+ (void) makeCube {
NSString *filePath = #"/Development/testNSDataProperty/test_cube_data.dat";
_cubeData = [[NSData alloc] initWithContentsOfFile:filePath];
}
#end
main.m:
[FxPlug makeCube];
NSLog (#"%#", [FxPlug cubeData]);