当允许访问我的应用程序时，Dropbox API给我错误403

Question

我正在尝试在flutter / objective-c中使用Dropbox API。对Objective-c编程来说是全新的，所以如果让我完全理解就有点困难了。

每次我允许用户访问时，都会出现错误403或访问被拒绝。

#import <ObjectiveDropboxOfficial/ObjectiveDropboxOfficial.h>

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  [DBClientsManager setupWithAppKey:@"APPKEY"];
  [GeneratedPluginRegistrant registerWithRegistry:self];
  // Override point for customization after application launch.
  FlutterViewController* controller = (FlutterViewController*)self.window.rootViewController;
  FlutterMethodChannel* dropBoxLogin = [FlutterMethodChannel methodChannelWithName: @"xante.flutter.dev/dropbox" binaryMessenger: controller];
  [dropBoxLogin setMethodCallHandler: ^(FlutterMethodCall* call, FlutterResult result){
      if ([@"retrieveAccessToken" isEqualToString:call.method]) {
        [self myButtonInControllerPressed];


      }
      else{
        result(FlutterMethodNotImplemented);
      }
  }];
  return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

- (void)myButtonInControllerPressed {
  [DBClientsManager authorizeFromController:[UIApplication sharedApplication]
                                 controller:[[self class] topMostController]
                                    openURL:^(NSURL *url) {
                                      [[UIApplication sharedApplication] openURL:url];
                                    }];
}

+ (UIViewController*)topMostController
{
    UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;

    while (topController.presentedViewController) {
        topController = topController.presentedViewController;
    }

    return topController;
}

- (BOOL)application:(UIApplication *)app openURL:(NSURL *)url
            options:(NSDictionary<UIApplicationOpenURLOptionsKey,id> *)options {
  DBOAuthResult *authResult = [DBClientsManager handleRedirectURL:url];
  if (authResult != nil) {
    if ([authResult isSuccess]) {
      NSLog(@"Success! User is logged into Dropbox.");
    } else if ([authResult isCancel]) {
      NSLog(@"Authorization flow was manually canceled by user!");
    } else if ([authResult isError]) {
      NSLog(@"Error: %@", authResult);
    }
  }
  return NO;
}

我很好奇我是否在错误的位置放了[DBClientsManager setupWithAppKey:@"APPKEY"];。