好的，这是一个如何子类化的示例NSURL协议 http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSURLProtocol_Class/Reference/Reference.html并提供图像（图片1.png) 已经在捆绑包中。下面是子类的标头、实现以及如何在 viewController（不完整的代码）和本地 html 文件（可以轻松与远程文件交换）中使用它的示例。我调用了自定义协议：myapp://正如您在底部的 html 文件中看到的那样。
谢谢你的提问！我自己问了这个问题很长一段时间，为了弄清楚这个问题所花费的每一秒都是值得的。
EDIT:如果有人在当前的 iOS 版本下运行我的代码遇到困难，请查看 sjs 的答案。当我回答这个问题时，它正在工作。他指出了一些有用的补充并纠正了一些问题，所以也给他支持。
这就是它在我的模拟器中的样子：
MyCustomURLProtocol.h
@interface MyCustomURLProtocol : NSURLProtocol
{
NSURLRequest *request;
}
@property (nonatomic, retain) NSURLRequest *request;
@end
MyCustomURLProtocol.m
#import "MyCustomURLProtocol.h"
@implementation MyCustomURLProtocol
@synthesize request;
+ (BOOL)canInitWithRequest:(NSURLRequest*)theRequest
{
if ([theRequest.URL.scheme caseInsensitiveCompare:@"myapp"] == NSOrderedSame) {
return YES;
}
return NO;
}
+ (NSURLRequest*)canonicalRequestForRequest:(NSURLRequest*)theRequest
{
return theRequest;
}
- (void)startLoading
{
NSLog(@"%@", request.URL);
NSURLResponse *response = [[NSURLResponse alloc] initWithURL:[request URL]
MIMEType:@"image/png"
expectedContentLength:-1
textEncodingName:nil];
NSString *imagePath = [[NSBundle mainBundle] pathForResource:@"image1" ofType:@"png"];
NSData *data = [NSData dataWithContentsOfFile:imagePath];
[[self client] URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
[[self client] URLProtocol:self didLoadData:data];
[[self client] URLProtocolDidFinishLoading:self];
[response release];
}
- (void)stopLoading
{
NSLog(@"something went wrong!");
}
@end
MyCustomProtocolViewController.h
@interface MyCustomProtocolViewController : UIViewController {
UIWebView *webView;
}
@property (nonatomic, retain) UIWebView *webView;
@end
MyCustomProtocolViewController.m
...
@implementation MyCustomProtocolViewController
@synthesize webView;
- (void)awakeFromNib
{
self.webView = [[[UIWebView alloc] initWithFrame:CGRectMake(20, 20, 280, 420)] autorelease];
[self.view addSubview:webView];
}
- (void)viewDidLoad
{
// ----> IMPORTANT!!! :) <----
[NSURLProtocol registerClass:[MyCustomURLProtocol class]];
NSString * localHtmlFilePath = [[NSBundle mainBundle] pathForResource:@"file" ofType:@"html"];
NSString * localHtmlFileURL = [NSString stringWithFormat:@"file://%@", localHtmlFilePath];
[webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:localHtmlFileURL]]];
NSString *html = [NSString stringWithContentsOfFile:localHtmlFilePath encoding:NSUTF8StringEncoding error:nil];
[webView loadHTMLString:html baseURL:nil];
}
文件.html
<html>
<body>
<h1>we are loading a custom protocol</h1>
<b>image?</b><br/>
<img src="myapp://image1.png" />
<body>
</html>
