Question

我创建的应用程序将使用本地图像和javascript / css文件在UIWebView上显示远程页面，以加快加载速度。我想避免使用缓存，因为要使其工作，必须首先加载所有内容。我在网上寻找可能的解决方案。这就是我所拥有的：

 NSURLRequest *urlrequest = [ [NSURLRequest alloc] initWithURL: [NSURL URLWithString:urlString] ];
    NSData *returnData = [ NSURLConnection sendSynchronousRequest:urlrequest returningResponse: nil error: nil ];
    NSString *HTMLData = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];


    NSString *resourcePath = [[NSBundle mainBundle] resourcePath];
    resourcePath = [resourcePath stringByReplacingOccurrencesOfString:@"/" withString:@"//"];
    resourcePath = [resourcePath stringByReplacingOccurrencesOfString:@" " withString:@"%20"];

    [webView loadHTMLString:HTMLData baseURL:
    [NSURL URLWithString: 
     [NSString stringWithFormat:@"file:/%@//",resourcePath]
     ]];

定义了urlString，我将文件移动到app bundle。

代码正常工作，因为我可以看到远程页面，但不存在图像或javascript文件。

Answer 1

我通过继承NSURLCache来解决这个问题。

首先，创建NSURLCache

的继承

#import "VURLCache.h"
#import <MobileCoreServices/UTType.h>

@implementation VURLCache

-(NSString*)mimeTypeForExtension:(NSString*)ext
{
    NSAssert( ext, @"Extension cannot be nil" );
    NSString* mimeType = nil;

    CFStringRef UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension,
        (CFStringRef)ext, NULL);
    if( !UTI ) return nil;

    CFStringRef registeredType = UTTypeCopyPreferredTagWithClass(UTI, kUTTagClassMIMEType);
    if( !registeredType ) // check for edge case
    {
        if( [ext isEqualToString:@"m4v"] )
                mimeType = @"video/x-m4v";
        else if( [ext isEqualToString:@"m4p"] )
                mimeType = @"audio/x-m4p";
        // handle anything else here that you know is not registered
    } else {
        mimeType = NSMakeCollectable(registeredType);
    }

    CFRelease(UTI);
    return mimeType;
}

-(void)parseBundleURL:(NSURL*)url 
                 name:(NSString**)name 
                  ext:(NSString**)ext 
      bundleDirectory:(NSString**)bundleDirectory {

    NSString* path = [url path];
    NSUInteger nameStart = NSNotFound;
    // locate the last '/'
    NSRange pathStop = [path rangeOfString:@"/" options:NSBackwardsSearch];
    if( 0 == pathStop.location ) {
        nameStart = 1;
    } else if ( NSNotFound != pathStop.location ) {
        // there is a path
        nameStart = pathStop.location+1;
        NSRange pathRange = NSMakeRange(0, nameStart);
        *bundleDirectory = [path substringWithRange:pathRange];
    }

    NSRange fileRange = NSMakeRange(nameStart, path.length - nameStart);
    if( fileRange.length > 0 ) {
        NSRange extStop = [path rangeOfString:@"." options:0 range:fileRange];
        if( NSNotFound != extStop.location ) {
            NSUInteger sep = extStop.location;
            NSRange nameRange = 
                NSMakeRange( nameStart, sep - nameStart);
            *name = [path substringWithRange:nameRange];
            NSRange extRange = 
                NSMakeRange( sep+1, path.length -(sep+1));
            *ext = [path substringWithRange:extRange];
        }
    }
}

-(NSCachedURLResponse*)bundleResourceForRequest:(NSURLRequest *)request {

    NSURL* url = [request URL];
    NSString* name = nil;
    NSString* ext = nil;
    NSString* bundleDirectory = nil;
    NSString* path = nil;

    [self parseBundleURL:url name:&name ext:&ext bundleDirectory:&bundleDirectory];

    if( name && ext ) {
        NSBundle* bundle = [NSBundle mainBundle];
        if( nil == bundleDirectory ) {
            path = [bundle pathForResource:name ofType:ext];
        } else {
            path = [bundle pathForResource:name ofType:ext inDirectory:bundleDirectory];
        }
    }

    NSCachedURLResponse* rep = nil;

    if( path ) {
        NSData* content = [NSData dataWithContentsOfFile:path];
        NSString* mime = [self mimeTypeForExtension:ext];
        NSString* encoding = nil;
        NSURLResponse* response = 
            [[NSURLResponse alloc] 
                    initWithURL:request.URL 
                       MIMEType:mime 
          expectedContentLength:[content length] 
               textEncodingName:encoding];
        rep = [[NSCachedURLResponse alloc] initWithResponse:response data:content];
    }

    return rep;
}

#pragma mark NSURLCache

-(NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request {
    NSURL* url = [request URL];
    if( [[url absoluteString] hasPrefix:VBUNDLE_URL_PREFIX] ) {
        return [self bundleResourceForRequest:request];
    }
    return [super cachedResponseForRequest: request];   
}

@end

然后，替换app delegate中的默认NSURLCache

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
NSString *docDir = [paths objectAtIndex:0];
NSString *path =  docDir; // the path to the cache file
NSUInteger discCapacity = 0;
NSUInteger memoryCapacity = 5120*1024;

VURLCache *cache = [[VURLCache alloc] initWithMemoryCapacity:memoryCapacity diskCapacity:discCapacity diskPath:path];
[NSURLCache setSharedURLCache:cache];
[cache release];

然后，您可以在应用包中加载文件。

例如，

这将显示您的应用图标。你也可以用它加载css。

UIWebView使用本地图像和javascript文件加载远程html页面

1 个答案: