问题描述
我的头文件定义如下：
#import <Foundation/Foundation.h>
@interface Warning: NSObject {
在我的.m文件中我做：
In my .m file I do:
NSXMLParser *parser = [[NSXMLParser alloc] initWithContentsOfURL:url];
[parser setDelegate:self];
这个编译并在3.0以下工作正常。
This compiles and works just fine under 3.0.
如果我尝试使用4.0编译，我会收到此错误：
If I try to compile with 4.0 I get this error:
如果我添加：
@interface Warning: NSObject <NSXMLParserDelegate> {
它用4.0编译好，但是当我尝试用3.0编译时，我得到：
It compiles fine with 4.0, but when I try to compile with 3.0 I get:
正确找到Foundation框架。添加NSXMLParser.h无济于事。
The Foundation framework is found correctly. Adding NSXMLParser.h doesn't help.
任何帮助都将不胜感激。
Any help would be appreciated.
谢谢
推荐答案
根据库参考文档，NSXMLParser不需要严格的NSXMLParserDelegate实现：
According to the library reference documentation, NSXMLParser doesn't require a strict NSXMLParserDelegate implementation :
- (void)setDelegate:(id)delegate
- (id)delegate
NSXMLParser动态检查所需的委托方法可用性。
NSXMLParser checks needed delegate methods availability on the fly.
如果NSXMLParser需要NSXMLParserDelegate完全实现，则访问者将是：
If NSXMLParser was requiring a NSXMLParserDelegate full implementation, the accessors would be :
- (void)setDelegate:(id<NSXMLParserDelegate>)delegate
- (id<NSXMLParserDelegate>)delegate
我猜这就是为什么框架中没有实际定义的NSXMLParserDelegate协议。
I guess that's why there is no NSXMLParserDelegate protocol actually defined in the framework.
所以，这个界面对我来说似乎是正确的：
So, that interface seems correct to me :
#import <Foundation/Foundation.h>
@interface Warning: NSObject {
你所要做的就是实施你需要的 。
All you have to do is implement the delegate methods you need for.
编辑：
您可以尝试使用预处理器宏来激活或停用协议使用声明：
You could try using preprocessor macros to activate or deactivate the protocol usage declaration :
#if __IPHONE_OS_VERSION_MIN_REQUIRED >= __IPHONE_4_0
@interface Warning: NSObject <NSXMLParserDelegate>
#else
@interface Warning: NSObject
#endif
{
// interface definition ...
我没有尝试使用4.0，但它适用于3.1和3.2之间的另一个例子
I didn't try this with 4.0, but it worked on another example between 3.1 and 3.2
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