Rxswift: "DataSource not set" error

[a83988029]

Short description of the issue:

I wrote a tableview like the example, but it report error "DataSource not set" , which I don't know where is wrong.

Expected outcome:

my app does not crash

What actually happens:

app crash

Self contained code example that reproduces the issue:

  //
//  WHSelectRegionController.swift
//  WormHole
//
//  Created by mac on 16/11/14.
//  Copyright © 2016年. All rights reserved.
//

import UIKit
import RxSwift
import RxCocoa
import RxDataSources

struct RegionModel {
    var name = "中国"
    var code = "86"
    var region = "CN"
}

class SelectRegionViewModel: NSObject {
    func getRegions() -> Observable<[SectionModel<String,RegionModel>]> {
        let regionModel1 = RegionModel()
        let regionModel2 = RegionModel()

        let regions = [regionModel1, regionModel2]
        let regions1 = [regionModel1, regionModel2]
        return Observable.just([SectionModel(model: "11", items: regions),SectionModel(model: "22", items: regions1)])
    }
}

class WHSelectRegionController: UIViewController {


    let datasources = RxTableViewSectionedReloadDataSource<SectionModel<String, RegionModel>>()
    let reuseId = "\(UITableViewCell.self)"
    let viewModel = SelectRegionViewModel()
    @IBOutlet weak var mainTable: UITableView!
    override func viewDidLoad() {
        super.viewDidLoad()
        title = "SelectRegion"

        view.addSubview(mainTable)
        mainTable.registerClass(UITableViewCell.self, forCellReuseIdentifier: reuseId)

        let datasource = self.datasources
        datasource.configureCell = {[weak self] aa,table,indexpath,region in
            guard let wself = self, let cell = wself.mainTable.dequeueReusableCellWithIdentifier(wself.reuseId) else{
                return UITableViewCell()
            }
            cell.textLabel?.text = region.name
            return cell
        }

        viewModel.getRegions()
            .bindTo(mainTable.rx_itemsWithDataSource(datasource))
            .addDisposableTo(DisposeBag())

    }



}


// If we can't get a self contained code example that reproduces the issue, there is a big chance we won't be able
// to help you because there is not much we can do.
//
// `Self contained code example` means:
//
// * that we should be able to just run the provided code without changing it.
// * that it will reproduce the issue upon running

RxSwift/RxCocoa/RxBlocking/RxTest version/commit

• RxCocoa (2.6.0):
  
  
  
  • RxSwift (~> 2.5)
  
  
• RxDataSources (0.9):
  
  
  
  • RxCocoa (~> 2.2)
  
  
  • RxSwift (~> 2.2)
  
  
• RxSwift (2.6.0)

Platform/Environment

• [x] iOS

How easy is to reproduce? (chances of successful reproduce after running the self contained code)

• [x] easy, 100% repro

Xcode version:

  Version 7.3 (7D175)

:warning: Fields below are optional for general issues or in case those questions aren't related to your issue, but filling them out will increase the chances of getting your issue resolved. :warning:

Installation method:

• [x] CocoaPods

I have multiple versions of Xcode installed:
(so we can know if this is a potential cause of your issue)

• [x] no

Level of RxSwift knowledge:
(this is so we can understand your level of knowledge
and formulate the response in an appropriate manner)

• [x] I have a small code base

[kzaher]

Hi @a83988029 ,

Fix for this is in rxswift-2.0 branch.

I'll try to publish it soon since I see there is still a lot of people using 2.x version.

[kzaher]

Hi @a83988029 ,

I think I might have confused your issue with one other old issue we had.

I believe that the problem is your case is that you've used dispose bag in a wrong way.

It should be

class WHSelectRegionController: UIViewController {
    let disposeBag = DisposeBag()

   override func viewDidLoad() {

      viewModel.getRegions()
            .bindTo(mainTable.rx_itemsWithDataSource(datasource))
            .addDisposableTo(disposeBag)
  }
}

[a83988029]

Why do I have to assign DisposeBag() to a let, then use it?

[kzaher]

Because DisposeBag will dispose all subscriptions it contains once it's being deallocated.

The wanted behavior is that the binding lasts until view controller deallocates.

This means

 viewModel.getRegions()
            .bindTo(mainTable.rx_itemsWithDataSource(datasource))
            .addDisposableTo(DisposeBag())

bind and then immediately unbind (because dispose bag) deallocates.

[a83988029]

get it. thankyou!

[kzaher]

I've made 2.6.1 release that improves this behavior and does crash the app, but using dispose bag in this way still isn't useful.