Question

我的应用程序具有相当简单的授权/身份验证，需要一些有关如何处理授权生命周期的帮助。这是它的主旨：

用户输入凭据进行登录，服务器使用令牌进行响应并存储在钥匙串中
该令牌用于每个后续URL请求（REST调用）的“授权”标头
令牌最终到期，服务器将响应401状态码
此时用户需要通过登录屏幕重新进行身份验证，以便我们获取新令牌并重试请求

这里有一些代码，代表了我现在能想到的最好的代码。

static NSString * _authorizationToken;
@implementation MyRestfulModel
+ (id) sharedRestfulModel
{
    // singleton model shared across view controllers
    static MyRestfulModel * _sharedModel = nil;
    @synchronized(self) {
        if (_sharedModel == nil) 
            _sharedModel = [[self init] alloc];
    }
    return _sharedModel;
}

+ (NSString *) authorizationToken
{
    if (!_authorizationToken)
        _authorizationToken = @"";
    return _authorizationToken;
}

+ (void) setAuthorizationToken: (NSString *token)
{
    _authorizationToken = token;
}

-(void) doSomeRestfulCall: (NSString *) restURL
        completionHandler: (void (^)(NSData * data)) callback
{
    // construct url path and request
    NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:restURL];
    [request setValue:MyRestfulModel.authorizationToken forHTTPHeaderField:@"Authorization"];
    [[[NSURLSession sharedSession] dataTaskWithRequest: request
                                     completionHandler:^(NSData *data, NSURLResponse * response, NSError * error) {

                    NSHTTPResponse * httpResponse = (NSHTTPResponse *) response;
                    if([httpResponse statusCode] == 401) {  // WHAT TO DO HERE ?

                        dispatch_sync(dispatch_get_main_queue(), ^{
                            MyAppDelegate * delegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];
                            [delegate showLoginViewController callback:^(NSString * username, NSString * newToken) {
                                // recreate the NSURLSession and NSURLConfiguration with the new token and retry
                                MyRestfulModel.authenticationToken = token;
                                [self doSomeRestfulCall:callback];
                            }];
                        }
                        return;
                    } else {
                        callback(data);
                    }
    }] resume];
}

我希望这样做，以便视图控制器永远不必担心由于令牌过期而重试呼叫，所有可怕的会话处理和身份验证都可以由一个对象完成。

我正在考虑尝试使用NSURLSessionDelegate，但我无法弄清楚w.r.t中的didReceiveChallenge部分。弹出登录视图控制器。我正在考虑的另一个选项是添加一个类似于完成处理程序的“retryHandler”，它将在用户重新进行身份验证后调用。

Answer 1

我想我找到了一个很好的解决方案。以“doSomeRestfulCall”方法为例。

-(void) doSomeRestfullCall: (NSString *) restURL
         completionHandler: (void (^)(NSData * data)) callback
{
    // construct url path and request
    NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:restURL];
    [request setValue:MyRestfulModel.authorizationToken forHTTPHeaderField:@"Authorization"];
    [[[NSURLSession sharedSession] dataTaskWithRequest: request
                                     completionHandler:^(NSData *data, NSURLResponse * response, NSError * error) {
                   NSHTTPResponse * httpResponse = (NSHTTPResponse *) response;
                   if([httpResponse statusCode] == 401) {
                        [LoginViewController showWithCompletion:^(NSString *username, NSString *token) {
                            NSLog(@"Retrying request after user reauthenticated");
                            MyRestfulModel.authorizationToken = token;
                            [self doSomeRestfulCall:restURL completionHandler:callback];
                        }];
                        return;
                   } else {
                       callback(data);
                   }
               }] resume];
}

然后登录视图控制器就会发生很多魔法。（如果您不想要自定义登录控制器，也可以使用警报视图，请查看此帖子：http://nscookbook.com/2013/04/ios-programming-recipe-22-simplify-uialertview-with-blocks/）

@interface LoginViewController
@property (copy) void(^completionBlock)(NSString * username, NSString * tokenCredentials);
@end

@implementation LoginViewController

+ (void) showWithCompletion: (void (^)(NSString * username, NSString * tokenCredentials))completion
{
    AppDelegate * appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    UIViewController * rootController = appDelegate.window.rootViewController;
    UIStoryboard * storyboard = rootController.storyboard;

    LoginViewController * controller = [storyboard instantiateViewControllerWithIdentifier:@"Login"];
    controller.completionBlock = completion;

    controller.delegate = wrapper;
    controller.modalPresentationStyle = UIModalPresentationFormSheet;
    [rootController presentViewController:controller animated:YES completion:nil];
}


//
// <code for contacting your authentication service>
//


-(void) loginSuccessful: (NSString *) username withTokenCredentials:(NSString *)token
{
    // <code to store username and token in the keychain>

    if (self.completionBlock)
        self.completionBlock(username, token);
}

iOS：使用NSURLSession进行身份验证和令牌过期

1 个答案: