Objective-C NSKeyedUnarchiver unloading - objective-c

Question

In some AppDelegate class I have property NSDictionary *dict;
In applicationDidFinishLaunching i'm loading it like:
dict = (NSDictionary*) [NSKeyedUnarchiver unarchiveObjectWithFile:
#"/Users/username/Desktop/storage"];
Then, I have Outlet for button click. But inside click-action handler I could not access to dict's elements. What am I doing wrong?
EDIT:
here's .h-file:
#import <Cocoa/Cocoa.h>
#interface tttAppDelegate : NSObject <NSApplicationDelegate> {
NSWindow *window;
NSDictionary *dict;
}
#property (assign) IBOutlet NSWindow *window;
- (IBAction)click:(id)sender;
#end
and .m-file:
#import "tttAppDelegate.h"
#implementation tttAppDelegate
#synthesize window;
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
dict = (NSDictionary*) [NSKeyedUnarchiver unarchiveObjectWithFile:#"/some/storage"];
NSLog(#">>>>>>> %#", [dict valueForKey:#"test"]); // ok
}
- (IBAction)click:(id)sender {
NSLog(#">>>>>>> %#", [dict valueForKey:#"test"]); // fail
}
#end

Answer 1

You should use property accessors instead of directly accessing your instance variables:
In your .h file:
#interface tttAppDelegate : NSObject <NSApplicationDelegate> {
NSWindow *window;
NSDictionary *dict;
}
#property (assign) IBOutlet NSWindow *window;
#property (nonatomic, retain) NSDictionary *dict;
- (IBAction)click:(id)sender;
#end
In your .m:
#implementation tttAppDelegate
#synthesize window;
#synthesize dict;
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
self.dict = (NSDictionary*) [NSKeyedUnarchiver unarchiveObjectWithFile:#"/some/storage"];
NSLog(#">>>>>>> %#", [self.dict valueForKey:#"test"]); // ok
}
- (IBAction)click:(id)sender {
NSLog(#">>>>>>> %#", [self.dict valueForKey:#"test"]); // fail
}
#end
There are several reasons for doing this, but the most important in this case is that that way the accessor methods can handle memory management of the instance variable.