使用自定义NSURLProtocol在UIWebView中通过AJAX调用加载文本文件失败 [英] Loading text file by AJAX call in UIWebView using custom NSURLProtocol fails
问题描述
我想使用 UiWebView 在iOS应用上显示网站。该站点的某些组件（即使用AJAX调用加载的Web服务结果）应替换为本地数据。
I want to display a website on an iOS app using a UiWebView. Some components of the site (namely the webservice results loaded using AJAX calls) should be replaced by local data.
请考虑以下示例：
text.txt：
foo
page1.html：
<html><head>
<title>test</title>
<script type="text/javascript" src="jquery.js"></script>
</head>
<body>
<div id="target"></div>
<script type="text/javascript">
function init(){
$.get("text.txt",function(text){
$("#target").text(text);
});
}
$(init);
</script>
</body></html>
查看控制器：
@interface ViewController : UIViewController <UIWebViewDelegate>
@property (nonatomic,assign) IBOutlet UIWebView *webview;
@end
@implementation ViewController
@synthesize webview;
//some stuff here
- (void)viewDidLoad
{
[super viewDidLoad];
[NSURLProtocol registerClass:[MyProtocol class]];
NSString *url = @"http://remote-url/page1.html";
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];
[request setCachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData];
[webview loadRequest:request];
}
@end
MyProtocol：
@interface MyProtocol : NSURLProtocol
@end
@implementation MyProtocol
+ (BOOL) canInitWithRequest:(NSURLRequest *)req{
NSLog(@"%@",[[req URL] lastPathComponent]);
return [[[req URL] lastPathComponent] caseInsensitiveCompare:@"text.txt"] == NSOrderedSame;
}
+ (NSURLRequest*) canonicalRequestForRequest:(NSURLRequest *)req{
return req;
}
- (void) startLoading{
NSLog(@"Request for: %@",self.request.URL);
NSString *response_ns = @"bar";
NSData *data = [response_ns dataUsingEncoding:NSASCIIStringEncoding];
NSURLResponse *response = [[NSURLResponse alloc] initWithURL:[self.request URL] MIMEType:@"text/plain" expectedContentLength:[data length] textEncodingName:nil];
[[self client] URLProtocol: self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
[[self client] URLProtocol:self didLoadData:data];
[[self client] URLProtocolDidFinishLoading:self];
[response release];
}
- (void) stopLoading{
NSLog(@"stopLoading");
}
@end
如果我不注册我的自定义URLProtocol页面正确显示。如果我调用了 startLoading（），则会加载内容，之后会触发 stopLoading（）。但是在UIWebView上根本没有任何事情发生。我试图做一些错误处理，但既没有抛出JS AJAX错误，也没有调用 UIWebViewDelegate 的 didFailLoadWithError 。
If I don't register my custom URLProtocol the page is displayed properly. If I do startLoading() is called, the content is loaded and stopLoading() is triggered afterwards. But on the UIWebView nothing happends at all. I tried to do some error-handling, but neither is a JS AJAX error thrown nor is didFailLoadWithError of the UIWebViewDelegate called.
我尝试了另一个场景并创建了一个只加载图片的HTML页面：
I tried another scenario and created a HTML page that just loads an image:
<img src="image.png" />
并修改了我的URLProtocol以处理图像的加载 - 这可以正常工作。也许这与AJAX调用有关？
and modified my URLProtocol to just handle the loading of the image - this works properly. Maybe this has anything to do with AJAX calls?
您是否知道问题可能是什么？
Do you have any idea what the problem might be?
提前致谢！
推荐答案
我遇到了同样的问题，经过几天的拔毛后终于解决了这个问题：
I had the same problem and finally solved it after days of hair pulling :
您的问题来自您创建响应的方式，您必须创建状态200响应并强制WebView在必要时允许跨域请求：
Your problem comes from the way you create the response, you have to create a status 200 response and force the WebView to allow cross-domain request if necessary :
NSDictionary *headers = @{@"Access-Control-Allow-Origin" : @"*", @"Access-Control-Allow-Headers" : @"Content-Type"};
NSHTTPURLResponse *response = [[NSHTTPURLResponse alloc] initWithURL:request.URL statusCode:200 HTTPVersion:@"1.1" headerFields:headers];
您可以在我的答案中看到我的完整工作实现：
You can see my full working implementation in my answer here :
希望这会有所帮助，
Vincent
Hope this helps, Vincent
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