objective-c – 在WebKit中,如何获取资源的内容？

首先,您需要弄清楚您有兴趣拦截哪些请求(或者所有这些请求,无论如何).我在我的WebResourceLoadDelegate中执行此操作.如果我关心请求,我将其替换为我自己的请求,将自己附加为属性.我稍后会在NSURLProtocol中使用该属性.

- (NSURLRequest*) webView:(WebView*)sender 
                 resource:(id)identifier 
          willSendRequest:(NSURLRequest*)request 
         redirectResponse:(NSURLResponse*)redirectResponse     
           fromDataSource:(WebDataSource*)dataSource
{
    // Am I interested in this request?
    if (/* figure out if you want it or not */) {
        NSMutableURLRequest* newRequest = [[request mutableCopy] autorelease];
        [NSURLProtocol setProperty:self forKey:@"MyApp" inRequest:newRequest];
        return newRequest;
    }
    else {  
        // Not interested,let it go through normally
        return request;
    }
}

我的NSURLProtocol看起来像这样.

@interface MyURLProtocol : NSURLProtocol {
    id _delegate;
    NSURLConnection* _connection;
    NSMutableData* _data;
}
@end

在我的NSURLProtocol子类中,我可以使用附加属性来查看是否应该拦截响应.

+ (BOOL) canInitWithRequest:(NSURLRequest*)request
{   
    id delegate = [NSURLProtocol propertyForKey:@"MyApp" inRequest:request];
    return (delegate != nil);
}

在initWithRequest中,我将委托移动到我的NSURLProtocol实例中,并从请求中删除该属性.当我实际尝试加载此请求时,这会阻止无限循环.

- (id) initWithRequest:(NSURLRequest*)theRequest 
        cachedResponse:(NSCachedURLResponse*)cachedResponse 
                client:(id<NSURLProtocolClient>)client
{
    // Move the delegate from the request to this instance
    NSMutableURLRequest* req = (NSMutableURLRequest*)theRequest;    
    _delegate = [NSURLProtocol propertyForKey:@"MyApp" inRequest:req];  
    [NSURLProtocol removePropertyForKey:@"MyApp" inRequest:req];

    // Complete my setup
    self = [super initWithRequest:req cachedResponse:cachedResponse client:client];
    if (self) {
        _data = [[NSMutableData data] retain];
    }
    return self;
}

剩下的就是库存URL加载的东西.

- (void) startLoading
{
    _connection = [[NSURLConnection connectionWithRequest:[self request] delegate:self] retain];
}

- (void) stopLoading
{
    [_connection cancel];
}

- (void)connection:(NSURLConnection*)conn didReceiveResponse:(NSURLResponse*)response 
{
    [[self client] URLProtocol:self didReceiveResponse:response cacheStoragePolicy:[[self request] cachePolicy]];
    [_data setLength:0];
}

- (void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
{
    [[self client] URLProtocol:self didLoadData:data];
    [_data appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection*)conn
{
    [[self client] URLProtocolDidFinishLoading:self];

    // Forward the response to your delegate however you like
    if (_delegate && [_delegate respondsToSelector:@selector(...)]) {
        [_delegate ... withRequest:[self request] withData:_data];
    }
}

- (NSURLRequest*)connection:(NSURLConnection*)connection willSendRequest:(NSURLRequest*)theRequest redirectResponse:(NSURLResponse*)redirectResponse
{
    return theRequest;
}

- (void)connection:(NSURLConnection*)conn didFailWithError:(NSError*)error 
{
    [[self client] URLProtocol:self didFailWithError:error];
}