Question

I’m currently trying to write my first CoreData-Application, which needs to access the applications delegate for some stuff. So I was trying to make a little variable inside my delegate which I wanted to read to determine if I got the correct delegate. However, it seems like I’m unable to access my delegate and create a new one instead.
Here is my code:

//delegate.h
#import <Cocoa/Cocoa.h>

@interface delegate_TestAppDelegate : NSObject <NSApplicationDelegate> {
@private
    NSWindow *window;
    NSString * myString;
}

@property (assign) IBOutlet NSWindow *window;
@property (retain) NSString * myString;

@end

//delegate.m
#import "delegate_TestAppDelegate.h"

@implementation delegate_TestAppDelegate

@synthesize window, myString;

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    self.myString = @"Hello, World";
    NSLog(@"In delegate: %@", self.myString);
}

@end

//MyClass.h
#import <Foundation/Foundation.h>
#import "delegate_TestAppDelegate.h"


@interface MyClass : NSObject {
@private
    delegate_TestAppDelegate * del;
}
- (IBAction)click:(id)sender;

@end

//MyClass.m
#import "MyClass.h"

@implementation MyClass

- (id)init
{
    self = [super init];
    if (self) {
        del = [[NSApplication sharedApplication] delegate];
    }

    return self;
}

- (void)dealloc
{
    [super dealloc];
}

- (IBAction)click:(id)sender {
    NSLog(@"Click: %@", del.myString);
}
@end

Strangely enough, this code returns “In delegate: Hello, World”, but “Click: (null)”
Where is my error?

Answer 1

I suspect you’re assigning del before anything has been assigned to the delegate property of the application. I’d recommend you get rid of the del pointer altogether, and simply call [[NSApplication sharedApplication] delegate] each time you need the delegate.