Obj-C API v2 Error Handling

For each API call, you'll want to handle both the route error (for errors specific to that call) as well as the general error (for errors that can happen on any call).

For the route specific error for createFolder, which is DBFILESCreateFolderError, there is only the isPath case, since that error doesn't have any other scenarios. (The example in the README is for the delete call, which has a different set of possible route-specific errors, under DBFILESDeleteError.)

To see what is possible for any particular error, I recommend checking the Objective-C SDK documentation for that error type, e.g., DBFILESCreateFolderError, which lists just isPath. (You can look at the HTTP documenation, as you linked to, but the names won't always be exactly the same, as they get translated slightly for the SDK.)

So, if DBFILESCreateFolderError isPath is true, you can then access the DBFILESWriteError in it via the path field.

Here's a more elaborate sample for createFolder showing that:

        [[client.filesRoutes createFolder:@"/test/path"] response:^(DBFILESFolderMetadata *result, DBFILESCreateFolderError *routeError, DBError *error) {
            if (result) {
                NSLog(@"%@\n", result);
            } else if (routeError) {
                NSLog(@"%@\n", routeError);
                if ([routeError isPath]) {
                    if ([routeError.path isConflict]) {
                        if ([routeError.path.conflict isFolder]) {
                            NSLog(@"Could not create folder because a folder already exists at path.");
                        } else {
                            // some other path conflict error:
                            NSLog(@"%@\n", routeError.path.conflict);
                        }
                    } else if ([routeError.path isMalformedPath]) {
                        NSLog(@"Could not create folder because the path is malformed.");
                    } else { // and so on for other errors as desired
                        // some other path error:
                        NSLog(@"%@\n", routeError.path);
                    }
                }
            } else if (error) {
                NSLog(@"%@\n", error);
            }
        }];