Question

I have started coding in Objective-C for several days, and I am really confused about delegation. Could any one help?

In MyClassA.h

@protocol MyClassADelegate <NSObject>

- (void)haveANewMessage:(NSString*)message;

@end

@interface myClassA : NSObject <NSStreamDelegate> {
    __unsafe_unretained id<MyDelegate> _delegate;
}
@property (nonatomic, assign) id<MyClassADelegate> delegate;

@end

In myClassB.h

@interface myClassB : NSViewController <MyTableViewDelegate,MyClassADelegate>

@property (nonatomic, strong) myClassA* instance;

@property (nonatomic, strong) IBOutlet NSTableView* tableView;

@property (nonatomic, strong) NSMutableArray* messages;

@end

In myClassA.m

I have

[self.delegate haveANewMessage:@"Messages"];

and in myClassB.m

I have

- (void) haveANewMessage:(NSString *)message{
    NSLog(@"Get here!");
    [self.messages addObject:message ];
    [self.tableView reloadData];
}

The problem is nothing is shown in my table view. Any help??
(Implemented Table-View Related Methods)

Answer 1

A few things to look into, in this order.

1. Is Get here! appearing in your logs to signify your delegate method is being fired properly?
2. Did you set self.delegate = myClassBInstance
3. Is your TableView Delegate/DataSource setup correctly?
4. Has self.messages been initialized?

And as a side note, in Objective-C it is frowned upon for your class names to start with a lowercase letter. Class names should be CamelCase starting with a capital letter and variables should be camelCase starting with a lowercase letter.