Question

PrefMySpotsViewCtrl.h

@class Location;

@interface PrefMySpotsViewCtrl : NSViewController
{
  NSTextField *locationSearchInput;
  NSString * enteredLocation;

  Location *l;
}

@property (nonatomic, retain) IBOutlet NSTextField *locationSearchInput;
@property (nonatomic, retain) NSString *enteredLocation;

PrefMySpotsViewCtrl.m

#import "Location.h"


- (void) controlTextDidChange:(NSNotification *)aNotification
{
   enteredLocation = [locationSearchInput stringValue];
   NSLog(@"in class:%@", enteredLocation);
   [l searchLocation];
}

Location.h

@class PrefMySpotsViewCtrl;

@interface Location : NSObject

{
  PrefMySpotsViewCtrl *p;  
}

- (void) searchLocation;

Location.m

#import "Location.h"
#import "PrefMySpotsViewCtrl.h"

@implementation Location

- (void) searchLocation
{
   NSLog(@"out of class: %@", [p enteredLocation]);
}

User inputs a into locationSearchInput and here is the output

2012-09-30 10:18:12.915 MyApp[839:303] in class:
2012-09-30 10:18:12.917 MyApp[839:303] in class:a

searchLocation method is never executed.

If I do l = [[Location alloc] init]; , then searchLocation is executed but the output is null

2012-09-30 10:28:46.928 MyApp[880:303] in class:
2012-09-30 10:28:46.929 MyApp[880:303] out of class: (null)
2012-09-30 10:28:46.930 MyApp[880:303] in class:a
2012-09-30 10:28:46.931 MyApp[880:303] out of class: (null)

Any idea?

Thanks?

Answer 1

But, the question is : have you assigned a valid instance of the controller(PrefMySpotsViewCtrl) to the location object ?

I mean :

l = [[Location alloc] init];
l->p = self;
[l searchLocation];

Keep in mind that is better to declare the PrefMySpotsViewCtrl as a property in the Location declaration, something like the following :

@interface Location : NSObject
{
  PrefMySpotsViewCtrl *p;  
}
@property (nonatomic, assign) PrefMySpotsViewCtrl *p;

And then assign it using the property setter :

l = [[Location alloc] init];
l.p = self;
[l searchLocation];

EDIT

Since from the comments below seems that the OP didn’t understand the logic, i post a simple example to let him understand better :

1) ClassA declaration :

@interface ClassA : NSObject
@property(nonatomic,retain) NSString *ABC;
@end

2) ClassB declaration:

@interface ClassB : NSObject 
@property(nonatomic,assign) ClassA *p;
-(void) printClassAvar;
@end

@implementation ClassB
-(void) printClassAvar {
    NSLog(@"Variable = %@", [self.p ABC]);
}
@end

3) Usage :

ClassA *a = [ClassA new];
a.ABC = @"XZY";
ClassB *b = [ClassB new];
b.p = a;
[b printClassAvar];