验证令牌刷新处理过程

Question

我的应用与后端服务器通信。在每个Web请求中，都会检查身份验证令牌是否有效。如果不是应用程序请求新令牌。这在第一个实例中工作正常。

但是现在我遇到了困难，即新令牌会在某个时间点传递。在此时间点到达之前，原始请求必须等待，必须通知repsective新的身份验证令牌可用且请求可以继续。

如何解决这个难题？进行身份验证令牌刷新的最佳方法是什么？

以下是我目前所做的事情：

ViewController.h

#import <UIKit/UIKit.h>

@interface LoginViewController : UIViewController <UIScrollViewDelegate>

-(IBAction)sandbox;

@end

ViewController.m - 包含重要部分

#import "ViewController.h"
#import "WebApi.h"

@interface LoginViewController ()

@end

@implementation LoginViewController

-(IBAction)sandbox {
    // Call the web request, if the auth token is expired
    // a new token shall be retrieved if allowed and proceed
    // with the web-request
    [[WebApi sharedInstance] sandbox]; 
}

@end

WebApi.h

#import "AFHTTPRequestOperationManager.h"
#import "SingletonClass.h"

@interface WebApi : AFHTTPRequestOperationManager <SingletonDelegate>

@property (nonatomic, strong) SingletonClass *sshare;

+(WebApi*)sharedInstance;

-(void)sandbox;
-(void)refreshVilitToken; 

@end

WebApi.m

#import "WebApi.h"

#define kApiHost @"http://192.168.1.157"

@implementation WebApi

-(WebApi*)initWithBaseURL:url {
    self = [super init];
    if (self != nil) {
        self.sshare = [SingletonClass sharedInstance];
    }
    return  self;
}

+(WebApi*)sharedInstance
{
    static WebApi *sharedInstance = nil;
    static dispatch_once_t oncePredicate;
    dispatch_once(&oncePredicate, ^{
        sharedInstance = [[self alloc] initWithBaseURL:[NSURL URLWithString:kApiHost]];
    });

    return sharedInstance;
}

-(void)sandbox {

    DLog(@"Sandbox call");

    NSString *URLString = [NSString stringWithFormat:@"%@/public/foo/sandbox", kApiHost];

    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];

    [self setAuthHeader:manager];

    [manager GET:URLString parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
        DLog(@"JSON: %@", responseObject);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        DLog(@"Error: %@, responseString: %@", error, operation.responseString);
    }];
}

-(void)setAuthHeader:(AFHTTPRequestOperationManager *)manager {

    if (self.sshare.hasCredentialsExpired) { // if token is expired!
        [self refreshToken];  // get a new token
        self.sshare.delegate = self;
        self.sshare.tokenInRefreshProcess = YES;  // token retrieving is in process
       // If new token is retrived the variable is set to NO
    }

    if (!self.sshare.tokenInRefreshProcess) {  // if the new token is available, then ...
        // How do I ensure that this is proceeded first if the token is available?

        NSDictionary *access = self.sshare.getAccessCredentials;

        DLog(@"Token: %@ and id %@", access[@"token"], access[@"id"]);
        manager.securityPolicy.allowInvalidCertificates = YES;
        manager.requestSerializer = [AFHTTPRequestSerializer serializer];    
        [manager.requestSerializer setAuthorizationHeaderFieldWithUsername:access[@"token"]
                                                                      password:access[@"id"]];
    }
}

-(void)refreshToken {
    DLog(@"%@", self.sshare.database[@"foo"]);

    NSString *URLString = [NSString stringWithFormat:@"%@/public/foo/token/%@/%@", kApiHost, [self.sshare authKey], self.sshare.database[@"foo"][@"foo_refesh"]];
    DLog(@"URLString %@", URLString); 
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];

    [manager PUT:URLString parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {

        [self.sshare saveNewToken:responseObject];

    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        DLog(@"Error: %@, responseString: %@", error, operation.responseString);
    }];
}

// delegate, but I strugle to use this for every request...
// I could place here the -(void)sandbox call, but then I can only
// call this method, I want that this works for every web-request
-(void)didRefreshToken {
    DLog(@"DELEGATE     :: did refresh Vilit token!!");
}