UIWebView清除缓存

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

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

       NSURLCache *sharedCache = [[[NSURLCachealloc] initWithMemoryCapacity:cacheSizeMemorydiskCapacity:cacheSizeDisk diskPath:@"nsurlcache"] autorelease];

        [NSURLCachesetSharedURLCache:sharedCache];