objective-c - 通过委托(delegate)调用时无法识别协议(protocol)方法

Question

我的问题是当我调用协议(protocol)方法时 dataLoading通过委托(delegate)，它只是无法识别它 - 给出 expected identifier错误。

这是协议(protocol)/接口(interface)文件:

#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

这是实现文件:

#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

错误在这一行:selector:@selector([self.delegate dataLoading])
我确信这是我的一个愚蠢的错误，但我不明白为什么它不能识别该方法，因为委托(delegate)与协议(protocol)绑定(bind)......

Answer 1

你写的方式selector:@selector([self.delegate dataLoading])尝试使用是错误的:selector:@selector(dataLoading)反而。