目标C-“方法的重复声明"；编译错误 [英] Objective C - "Duplicate declaration of method" compilation error

问题描述

我有这段代码:

- (id) getSearchSuggestions:(NSString*)q;
- (NSOperationQueue*) getSearchSuggestions:(NSString*)q callback:(id<UserDelegate>)callback;
- (id) getSearchSuggestions;
- (NSOperationQueue*) getSearchSuggestions:(id<UserDelegate>)callback;

并且我Xcode在最后行上不断向我显示错误:

And I Xcode keeps showing me an error on the last line:

Duplicate declaration of method "getSearchSuggestions"

为什么?在我看来，签名都是不同的.

Why? It seems to me that the signatures are all different.

推荐答案

此签名:

- (id) getSearchSuggestions:(NSString*)q;

与该签名相同:

- (NSOperationQueue*) getSearchSuggestions:(id<UserDelegate>)callback;

所有对象指针均为id.因此，这两种方法都需要一个对象并返回一个对象.

All object pointers are id. So both of these are methods that take an object and return an object.

更好的名字的例子是:

- (id)searchSuggestionsForQueryString:(NSString*)q; // Or ForTag, or whatever "q" is
- (NSOperationQueue*)searchOperationQueueForQuery:(NSString*)q callback:(id<UserDelegate>)callback;
- (id)fetchSearchSuggestions;
- (NSOperationQueue*)searchOperationQueueWithCallback:(id<UserDelegate>)callback;

尚不清楚为什么要在此处返回操作队列，但这是用于执行此操作的方法的名称.

It's not exactly clear why you return an operation queue here, but this is the kind of name you'd use for a method that did that.

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