1

我在objective-c中使用工厂模式，但由于某种原因它从不调用子类的方法。我将通过代码解释：

// MailBoxViewController.m -- file using the factory:
SearchWorker* searchWorker = [SearchWorkerFactory getSearchWorker:param];
// whenever I call this method, it's always the one belonging to SearchWorker, 
// rather than any of it's children classes, even if on breakpoint here, searchWorker
// is of class type AllSearchWorker
[searchWorker search:[searchParams objectForKey:@"query"] withDelegate:self withSnippedDelims:snippetDelims startWithDB:dbNum];


// searchWorkerFactory.m
#import "SearchWorkerFactory.h"
#import "SearchWorker.h"
#import "AllSearchWorker.h"    
@implementation SearchWorkerFactory    
+(id)getSearchWorker:(SearchWorkerType)syncType {        
    if (syncType == SearchWorkerTypeAll) {
        AllSearchWorker* searchWorker = [[AllSearchWorker alloc] init];
        return searchWorker;
    }
    return nil;
}    
@end


// SearchWorker.h
@interface SearchWorker : NSObject
-(void)search:(NSString *)query withDelegate:(id)delegate withSnippedDelims:(NSArray *)snippedDelims startWithDB:(int)dbIndex;    
@property (assign) volatile BOOL cancelled; // flag for when we cancel a search op
@property (nonatomic,readwrite,retain) NSOperationQueue *operationQueue;
@end

// SearchWorker.m
@implementation SearchWorker
..
-(void)search:(NSString *)query withDelegate:(id)delegate withSnippedDelims:(NSArray *)snippedDelims startWithDB:(int)dbIndex {
    [NSException raise:NSInternalInconsistencyException
                format:@"You must override %@ in a subclass", NSStringFromSelector(_cmd)];
}
@end


// AllSearchWorker.h
@interface AllSearchWorker : SearchWorker
-(void)search:(NSString *)query withDelegate:(id)delegate withSnippetDelims:(NSArray *)snippetDelims startWithDB:(int)dbIndex; 
@end

// AllSearchWorker.m
@implementation AllSearchWorker 
..
- (void)search:(NSString*)query withDelegate:(id)delegate withSnippetDelims:(NSArray *)snippetDelims startWithDB:(int)dbIndex {
    // implementation
}
@end

所以我总是收到错误消息：

* 由于未捕获的异常“NSInternalInconsistencyException”而终止应用程序，原因：“您必须在子类中覆盖 search:withDelegate:withSnippedDelims:startWithDB:”*首先抛出调用堆栈：

知道为什么会这样吗？另外，如果我控制单击该方法search:withDelegate:withSnippedDelims:startWithDB，xcode 会立即跳转到SearchWorker.m（即它没有给我一个存在此方法的文件列表）.. 如果我从中删除该方法SearchWorker.m，它会抱怨该方法不存在。 . 想法？

4

1 回答 1

3

Those are two different methods. You have used snipped in the superClass and snippet in the subClass

-(void)search:(NSString *)query withDelegate:(id)delegate withSnippetDelims:(NSArray *)snippetDelims startWithDB:(int)dbIndex; 
                                                                    ^

-(void)search:(NSString *)query withDelegate:(id)delegate withSnippedDelims:(NSArray *)snippedDelims startWithDB:(int)dbIndex {
                                                                    ^
于 2013-04-11T08:04:54.547 回答