iOS關於Cookie驗證登錄狀態

1、第一次進入應用，登錄獲取Cookie，此時如果用到的是AFN去獲取接口數據，Cookie已經寫入了，所以無需處理，每次請求的時候，會自動將該cookie傳給后台去驗證

2、將Cookie緩存到本地：

                NSData *cookiesData = [NSKeyedArchiver archivedDataWithRootObject: [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookies]];
                NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
                [defaults setObject: cookiesData forKey:@"Cookie"];
                [defaults synchronize];

3、當第二次進入應用的時候，先判斷NSUserDefault是否有緩存的Cookie，如果有，需要將cookie寫入，然后進入應用

                NSArray *cookies = [NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:@"Cookie"]];
                NSHTTPCookieStorage * cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
                for (NSHTTPCookie * cookie in cookies){
                    [cookieStorage setCookie: cookie];
                }

4、當用戶選擇退出登錄，需要清除緩存中的cookie，同時要將NSUserDefault中的Cookie刪除

（1）清除請求頭中的Cookie：

                NSHTTPCookieStorage *manager = [NSHTTPCookieStorage sharedHTTPCookieStorage];
                NSArray *cookieStorage = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookies];
                for (NSHTTPCookie *cookie in cookieStorage) {
                    [manager deleteCookie:cookie];
                }

（2）清除NSUserDefault中的Cookie

               [[NSUserDefaults standardUserDefaults] removeObjectForKey:@"Cookie"];

               [defaults synchronize];

 注意：關於Cookie還有有效期，就看后台怎么定義，前端只要判斷是否過了有效期，如果過了有效期，如果過了有效期，就需要用戶重新登錄，反之則不需要