Cant call delegate method from my protocol class

Question

I have a protocol in one class:

@protocol DataStorageManager

- (void) saveFile;

@end

@interface DataManager : NSObject
{
    id <DataStorageManager> delegate;
}

@property (nonatomic, assign) id<DataStorageManager> delegate;

//methods

@end

and its implementation:

@implementation DataManager

@synthesize delegate;

@end

and I have another class which is the adapter between the first and the third one:

#import "DataManager.h"
#import "DataPlistManager.h"

@interface DataAdapter : NSObject <DataStorageManager>

@property (nonatomic,strong) DataPlistManager *plistManager;
- (void) saveFile;

@end

and its implementation

#import "DataAdapter.h"

@implementation DataAdapter

-(id) initWithDataPlistManager:(DataPlistManager *) manager
{
    self = [super init];
    self.plistManager = manager;
    return self;
}

- (void) saveFile
{
    [self.plistManager savePlist];
}

@end

So when I in first method try to call my delegate method like this

[delegate saveFile];

Nothing happened. I don't understand what's wrong with the realization - it's a simple adapter pattern realization. So I need to use the delegate which will call the methods from the third class. Any help?

score 2 · Accepted Answer · answered Sep 05 '13 at 12:55

2

You are not setting the delegate property. You need to do this,

-(id) initWithDataPlistManager:(DataPlistManager *) manager
{
    self = [super init];
    self.plistManager = manager;
    self.plistManager.delegate = self;
    return self;
}

Also, in DataManager class remove the ivar declaration, just declaring property is sufficient, the ivar gets automatically created. Call the delegate method as below,

if([self.delegate respondsToSelector:@selector(saveFile)] {
    [self.delegate saveFile]; 
}

Hope that helps!

answered Sep 05 '13 at 12:55

Amar

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now there is an error _Property 'delegate' not found on object of type 'DataPlistManager *'_ What's wrong now? – ShurupuS Sep 05 '13 at 16:38
@ShurupuS Are you sure you want to pass `DataPlistManager` instance in `initWithDataPlistManager:` method or should it be `DataManager` instance instead? – Amar Sep 06 '13 at 06:49
What is `DataPlistManager` class anyways? Should it be subclass of `DataManager` class? – Amar Sep 06 '13 at 06:50
@Aamar DataPlistManager is just a class which contain some methods for work with plist. I try to use the adapter pattern - the main idea that I can easily change the class for working with different formats of files (DataPlistManager) without many changes in code. So in adapter I should call the methods from DataPlistManager. Sorry, I'm the new one in iOS dev and may be my description isn't complete. – ShurupuS Sep 06 '13 at 07:00
@ShurupuS So in the above code, you expect `DataPlistManager` to call the delegate method which is implemented by `DataAdapter`? If that is the case, I think `DataPlistManager` should be subclass of `DataManager`. – Amar Sep 06 '13 at 07:04
Ohhh... I totally confused with this case.. As I see `DataManager` will take somehow `DataStorageManager` which is a `DataAdapter` and `Data Adaptor` will use tghe present DataPlistManager class for all the next work with plist file.. That's how I would like to use all this construction. – ShurupuS Sep 06 '13 at 07:13
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/36907/discussion-between-shurupus-and-amar) – ShurupuS Sep 06 '13 at 07:15
1

@ShurupuS Then in that case, in your `DataManager` class, you need to write something like this:: `self.delegate=adapterInstance`, this will make the `DataAdapter` instance the delegate, as required. Hope you get my point. – Amar Sep 06 '13 at 07:15

score 1 · Answer 2 · edited May 23 '17 at 11:49

In your case you forget to set your protocol delegate and also need to call protocol method
by self.delegate....

I just Give Basic Idea for how to Create Protocol

Cant call delegate method from my protocol class

2 Answers2

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