Question

My problem is that when I am calling the protocol method dataLoading via the delegate, it just doesn’t recognize it – giving an expected identifier error.

Here is the protocol/interface file:

#import <Foundation/Foundation.h>

@class LoaderView;

@protocol DataLoaderProtocol <NSObject>

@required
- (void) dataLoading;
- (void) doneLoading;

@end

@interface DataLoader : NSObject {

}

@property (retain) id <DataLoaderProtocol> delegate;
@property (retain, nonatomic) LoaderView *loader;

- (id) initWithDelegate: (id <DataLoaderProtocol>) delegate;
- (void) start;

@end

And here is the implementation file:

#import "DataLoader.h"
#import "LoaderView.h"


@implementation DataLoader

@synthesize delegate = _delegate;
@synthesize loader = _loader;

- (id) initWithDelegate: (id <DataLoaderProtocol>) delegate
{
    self.delegate = delegate;

    return self;
}

- (void) start
{
    NSOperationQueue *queue = [NSOperationQueue new];
    NSInvocationOperation *operation = [[NSInvocationOperation alloc] 
                                        initWithTarget:self.delegate
                                        selector:@selector([self.delegate dataLoading]) 
                                        object:nil];
    [queue addOperation:operation]; 
    [operation release];
}

@end

The error is at this line: selector:@selector([self.delegate dataLoading])

I’m sure this is a stupid mistake on my part, but I don’t understand why it’s not recognizing that method, since the delegate is tied in with the protocol…

Answer 1

The way you wrote selector:@selector([self.delegate dataLoading]) is wrong try using : selector:@selector(dataLoading) instead.