WKWebView 怎么保存Cookie，遇到重定向后怎么处理

用了网上别人发的一个方法后，navigation是有写入cookie，但是遇到H5重定向后，cookie好像是不被识别 还是被清空了

// 页面加载完成之后调用
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation{
    //取出cookie
    NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
    //js函数
    NSString *JSFuncString =
    @"function setCookie(name,value,expires)\
    {\
    var oDate=new Date();\
    oDate.setDate(oDate.getDate()+expires);\
    document.cookie=name+'='+value+';expires='+oDate+';path=/'\
    }\
    function getCookie(name)\
    {\
    var arr = document.cookie.match(new RegExp('(^| )'+name+'=({FNXX==XXFN}*)(;|$)'));\
    if(arr != null) return unescape(arr[2]); return null;\
    }\
    function delCookie(name)\
    {\
    var exp = new Date();\
    exp.setTime(exp.getTime() - 1);\
    var cval=getCookie(name);\
    if(cval!=null) document.cookie= name + '='+cval+';expires='+exp.toGMTString();\
    }";

    //拼凑js字符串
    NSMutableString *JSCookieString = JSFuncString.mutableCopy;
    for (NSHTTPCookie *cookie in cookieStorage.cookies) {
        NSString *excuteJSString = [NSString stringWithFormat:@"setCookie('%@', '%@', 1);", cookie.name, cookie.value];
        [JSCookieString appendString:excuteJSString];
    }
    //执行js
    [webView evaluateJavaScript:JSCookieString completionHandler:^(id obj, NSError * _Nullable error) {
        NSLog(@"%@",error);
    }];
}