首先添加一個按鈕，點擊它的時候執(zhí)行清緩存和cookie操作，這里我重寫了導(dǎo)航的返回按鈕：

-(void)leftBarButtonClicked{
    _webView = nil;
    [self cleanCacheAndCookie];
    [self.navigationController popViewControllerAnimated:YES];
}

/**清除緩存和cookie*/
- (void)cleanCacheAndCookie{
    //清除cookies
    NSHTTPCookie *cookie;
    NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
    for (cookie in [storage cookies]){
        [storage deleteCookie:cookie];
    }
    //清除UIWebView的緩存
    [[NSURLCache sharedURLCache] removeAllCachedResponses];
    NSURLCache * cache = [NSURLCache sharedURLCache];
    [cache removeAllCachedResponses];
    [cache setDiskCapacity:0];
    [cache setMemoryCapacity:0];
}