UIWebView清除緩存

        int cacheSizeMemory = 4*1024*1024; // 4MB

        int cacheSizeDisk = 32*1024*1024; // 32MB

        NSURLCache *sharedCache = [[[NSURLCache alloc] initWithMemoryCapacity:cacheSizeMemory diskCapacity:cacheSizeDisk diskPath:@"nsurlcache"] autorelease];

        [NSURLCache setSharedURLCache:sharedCache];