Question

我需要使用我的应用登录Facebook，获取一些数据，完成后，还要登录Firebase。我正在使用调度队列，但它不起作用。我的积木不会等到对方完成。

这是我的代码：

dispatch_queue_t loginQueue = dispatch_queue_create("com.balazsvincze.loginQueue", DISPATCH_QUEUE_SERIAL);


//Log in to Facebook
    dispatch_async(loginQueue, ^{
        FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init];
        [login logInWithReadPermissions: @[@"public_profile",@"user_friends"] fromViewController:viewController handler:^(FBSDKLoginManagerLoginResult *result, NSError *error) {

            if(!error){
                NSLog(@"Logged into Facebook");
                self.facebookUserID = [[FBSDKAccessToken currentAccessToken] userID];

                //Load my profile
                [FBSDKProfile loadCurrentProfileWithCompletion:^(FBSDKProfile *profile, NSError *error){
                    if(!error){
                        self.name = profile.name;
                    }

                    else{
                        NSLog(@"Could not load profile: %@",error);
                        completionResult(NO);
                        return;
                    }

                }];
            }

            else{
                NSLog(@"Could not login: %@",error);
                completionResult(NO);
                return;
            }

        }];
    });

    //Log in to Firebase
    dispatch_async(loginQueue, ^{
        FIRAuthCredential *credential = [FIRFacebookAuthProvider credentialWithAccessToken:[FBSDKAccessToken currentAccessToken].tokenString];

        [[FIRAuth auth] signInWithCredential:credential  completion:^(FIRUser *user, NSError *error) {

            if(!error){
                NSLog(@"Logged into Firebase");
                self.firebaseUserID = user.uid;
            }

            else{
                NSLog(@"Could not login: %@",error);
                completionResult(NO);
                return;
            }
        }];
    });

有什么想法吗？谢谢！

Answer 1

拨打电话，在Facebook的完成处理程序中登录Firebase，它将全部按预期工作

Answer 2

虽然您要在串行调度队列上调度异步任务，但这些任务本身会调度异步任务然后结束;所以你的任务已经完成，但登录没有。

正如@Rob建议的那样，使用NSOperation之类的代码将代码拆分为单独的任务将会产生更清晰，更具伸缩性的代码。

但是，以下是在异步操作完成时如何使用dispatch_group和dispatch_group_notify来安排某些代码：

dispatch_group_t dispatchGroup = dispatch_group_create();

//Log in to Facebook
dispatch_group_enter(dispatchGroup);

FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init];
[login logInWithReadPermissions: @[@"public_profile",@"user_friends"] fromViewController:viewController handler:^(FBSDKLoginManagerLoginResult *result, NSError *error) {

    if(!error){
        NSLog(@"Logged into Facebook");
        self.facebookUserID = [[FBSDKAccessToken currentAccessToken] userID];

        //Load my profile
        dispatch_group_enter(dispatchGroup);
        [FBSDKProfile loadCurrentProfileWithCompletion:^(FBSDKProfile *profile, NSError *error){
            if(!error){
                self.name = profile.name;
            }
            else{
                NSLog(@"Could not load profile: %@",error);
                completionResult(NO);
            }
            dispatch_group_leave(dispatchGroup);
        }];
    }
    else{
        NSLog(@"Could not login: %@",error);
        completionResult(NO);
    }
    dispatch_group_leave(dispatchGroup);
}];

//Log in to Firebase
dispatch_group_enter(dispatchGroup);

FIRAuthCredential *credential = [FIRFacebookAuthProvider credentialWithAccessToken:[FBSDKAccessToken currentAccessToken].tokenString];

[[FIRAuth auth] signInWithCredential:credential  completion:^(FIRUser *user, NSError *error) {

    if(!error){
        NSLog(@"Logged into Firebase");
        self.firebaseUserID = user.uid;
    }

    else{
        NSLog(@"Could not login: %@",error);
        completionResult(NO);
    }
    dispatch_group_leave(dispatchGroup);
}];

dispatch_group_notify(dispatchGroup,dispatch_get_main_queue(),^{
    NSLog(@"All login tasks completed");
    // Do whatever
});

串口调度队列不等待

2 个答案: