Question

我正在注册NSURLProtocol的实现来对某些URL请求进行一些自定义处理（我通过在它们上设置属性来标记这些请求）。这些URL请求来自UIWebView的加载方法。

创建UI网页视图（启动后首次加载）
加载内容
销毁网络视图
创建新的Web视图（后续加载）
加载内容

我发现第2步和第5步之间存在明显不同的行为。我的NSURLProtocol实现管理缓存数据，旨在处理请求。如果我在请求中没有检测到我的属性，我会再次检查特定的URL（用于调试）。无论哪种情况，canInitWithRequest都会返回YES：

发布后首次加载：

2014-10-15 11:37:11.403 MYApp[5813:60b] MYURLProtocol canInitWithRequest: Matched property in request: <0x15ebbb40> https://example.com/ 
2014-10-15 11:37:11.404 MYApp[5813:60b] MYURLProtocol canInitWithRequest: Matched property in request: <0x15dc8da0> https://example.com/ 
2014-10-15 11:37:11.409 MYApp[5813:60b] MYURLProtocol canInitWithRequest: Matched property in request: <0x15ee5ef0> https://example.com/ 
2014-10-15 11:37:11.409 MYApp[5813:60b] MYURLProtocol canInitWithRequest: Matched property in request: <0x15ee6240> https://example.com/ 
2014-10-15 11:37:11.410 MYApp[5813:60b] MYURLProtocol initWithRequest:cachedResponse:client: Request: https://example.com/
2014-10-15 11:37:11.411 MYApp[5813:60b] MYURLProtocol canInitWithRequest: Matched property in request: <0x15ee69d0> https://example.com/ 
2014-10-15 11:37:11.415 MYApp[5813:9c07] MYURLProtocol startLoading Loading <0x15ee6240> https://example.com/ 
... A bunch of loading of assets occurs (cached responses) ...
2014-10-15 11:37:12.497 MYApp[5813:60b] MyWebViewController webViewDidFinishLoad: Finished loading

其他人已经指出，协议有多个关于同一资产的调用，这不是一个问题，尽管有趣的是要注意每次使用新对象调用它时，它是第4个（ 4）传递给startLoading的对象。不过，这里没有真正的担忧。

后续加载：

2014-10-15 11:11:27.466 MYApp[5782:60b] MYURLProtocol canInitWithRequest: Matched property in request: <0x1727c310> https://example.com/ 
2014-10-15 11:11:27.467 MYApp[5782:60b] MYURLProtocol canInitWithRequest: Matched property in request: <0x145b1d90> https://example.com/ 
2014-10-15 11:11:27.488 MYApp[5782:560f] MYURLProtocol canInitWithRequest: Matched URL in request: <0x17266060> https://example.com/
2014-10-15 11:11:27.669 MYApp[5782:60b] MYWebViewController webViewDidFinishLoad: Finished loading

在我看来，这是出乎意料的行为。看来，第三次将属性传递给canInitWithRequest时，属性已从请求中删除，然后，即使我们回复YES，我们也从未真正进入过 - 该页面只是返回到完整的UIWebView，没有后续的资产请求。以下是创建请求时的样子：

NSURLRequest *request = [NSURLRequest requestWithURL:myURL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
[self.webView loadRequest:request];

为什么，当我说我的协议可以处理请求时，是否没有机会这样做？我的猜测是答案在于UIWebView本身的实现。如果我真的希望我的协议成为负责的实体加载，有关如何解决这个问题的任何想法吗？

Answer 1

*** Way to clear the cache of webview **********
Follow this code:

NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
    for (NSHTTPCookie *cookie in [storage cookies]) {
        [storage deleteCookie:cookie];
    }
    [[NSUserDefaults standardUserDefaults] synchronize];

Answer 2

我能够通过缓存清除UIWebView缓存来解决此问题，同时不破坏NSURLCache。

在原始请求的查询参数中添加一个唯一的参数。我选择'key = 000000'，其中值为零导数的六位数随机数。
在协议中，删除canonicalRequestForRequest:和initWithRequest:cachedResponse:client

我的剥离代码看起来像这样（可能有一种更简洁的方法来剥离参数，但这有效）：

+ (NSURLRequest *)canonicalRequestForRequest:(NSURLRequest *)request
{
    NSURLRequest *canonicalRequest = request;
    BOOL myProtocolRequest = [[NSURLProtocol propertyForKey:kMYProtocolRequest inRequest:request] boolValue];
    if (myProtocolRequest)
    {
        NSMutableURLRequest *mutableRequest = [request mutableCopyWorkaround];
        NSString *originalURLString = mutableRequest.URL.absoluteString;
        NSString *regexString = [NSString stringWithFormat:@"(?:[?&])(key=[[:digit:]]{%d}&*)", kMYKeyLength];

        NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regexString options:0 error:0];
        NSTextCheckingResult *result = [regex firstMatchInString:originalURLString options:0 range:NSMakeRange(0, originalURLString.length)];
        if (result.numberOfRanges > 1)
        {
            NSRange keyRange = [result rangeAtIndex:1];
            NSLog(@"Removing '%@' from request", [originalURLString substringWithRange:keyRange]);
            NSString *replacementURLString = [originalURLString stringByReplacingCharactersInRange:keyRange withString:@""];
            mutableRequest.URL = [NSURL URLWithString:replacementURLString];
            canonicalRequest = mutableRequest;
        }
    }

    return canonicalRequest;
}

我的初始化代码如下：

- (id)initWithRequest:(NSURLRequest *)request cachedResponse:(NSCachedURLResponse *)cachedResponse client:(id<NSURLProtocolClient>)client
{
    self = [super initWithRequest:[MYURLProtocol canonicalRequestForRequest:request] cachedResponse:cachedResponse client:client];
    return self;
}

我不喜欢我必须这样做，但我终于得到了我想要的行为。希望它可以帮助那里的人。

在对canInitWithRequest的YES响应之后，不要求NSURLProtocol加载

2 个答案: