ios - 向协议(protocol)添加参数(委托(delegate))

Question

我想向委托(delegate)方法添加一个参数(来自 NSXMLParser 委托(delegate))

这是目前的方法:

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
    // save the characters for the current item...
    if ([string   isEqual: @"off"]) {
         myObject.isON = NO; //doesn't know what is myObject
    }

我想要什么:

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string:(MyObject*)anObject{
    // save the characters for the current item...
    if ([string   isEqual: @"off"]) {
         anObject.isON = NO;
    }

谢谢

Answer 1

首先你需要继承你的 NSXMLParser，添加新的 delegate 属性，调用它 subclassDelegate 或类似的东西，这样你就可以区分 super 类的委托(delegate)。在 init 中是你父类(super class)的委托(delegate) self.delegate = self;

响应委托(delegate)方法并将您不想覆盖的方法转发给 self.subclassDelegate 响应您想要覆盖的方法并在您的子类协议(protocol)中覆盖它。

例子如下:

    @protocol  MyXMLParserDelegate;
@interface MyXMLParser : NSXMLParser<NSXMLParserDelegate>
@property (weak) id<MyXMLParserDelegate> subclassDelegate;
@end

@protocol  MyXMLParserDelegate <NSObject>
- (void)parserDidStartDocument:(NSXMLParser *)parser;
// this is the method that you override
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string withObject:(id)object;
@end

然后在.m

@implementation MyXMLParser

- (id)init
{
    self = [super init];
    if(self) {
        self.delegate = self;
    }
    return self;
}


#pragma mark - repspond to NSXMLParser delegate

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    [self.subclassDelegate parser:parser foundCharacters:string withObject:yourObject];
}