Protocol method not being recognized when called via delegate

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...

user756245 · Accepted Answer · 2011-07-12 15:36:21Z

4

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

answered Jul 12, 2011 at 15:36

user756245

Sign up to request clarification or add additional context in comments.

1 Comment

xil3 Over a year ago

Doh!! Yea you're right, because I already specified the target! What a stupid mistake.

Tim Reddy · Accepted Answer · 2011-07-12 15:38:26Z

1

I don't know if self is defined yet when you call initWithDelegate. That may be messing up things downstream...

Try:

- (id) initWithDelegate: (id <DataLoaderProtocol>) delegate {
    self = [super init];
    if(self) {
        self.delegate = delegate
    }
    return self;
}

answered Jul 12, 2011 at 15:38

Tim Reddy

4,4482 gold badges45 silver badges77 bronze badges

1 Comment

user756245 Over a year ago

right, and don't we need to make a direct assignement too ? delegate = [aDelegate retain];

octy · Accepted Answer · 2011-07-12 15:39:45Z

1

You're passing a selector (i.e. SEL type), therefore you would need to write this:

NSInvocationOperation *operation = 
    [[NSInvocationOperation alloc] 
        initWithTarget:self.delegate
              selector:@selector(dataLoading) // the name of the selector here 
                object:nil];

answered Jul 12, 2011 at 15:39

octy

6,5351 gold badge30 silver badges38 bronze badges

Collectives™ on Stack Overflow

Protocol method not being recognized when called via delegate

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related