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Spots is a cross-platform view controller framework for building component-based UIs. The internal architecture is built using generic view models that can be transformed both to and from JSON. So, moving your UI declaration to a backend is as easy as pie. Data source and delegate setup is handled by Spots, so there is no need for you to do that manually. The public API is jam-packed with convenience methods for performing mutation, it is as easy as working with a regular collection type.

Table of Contents

Spots Icon

Key features

  • JSON based views that could be served up by your backend.
  • Live editing.
  • View based caching for controllers, table and collection views.
  • Supports displaying multiple collections, tables and regular views in the same container.
  • Features both infinity scrolling and pull to refresh (on iOS), all you have to do is to setup delegates that conform to the public protocols on Controller.
  • No need to implement your own data source, every Spotable object has their own set of Item’s. which is maintained internally and is there at your disposable if you decide to make changes to them.
  • Easy configuration of collection views, table views and any custom spot implementation that you add. This improves code reuse and helps to theme your app and ultimately keep your application consistent.
  • Support custom Spots, all you need to do is to conform to Spotable
  • A rich public API for appending, prepending, inserting, updating or deleting Items.
  • Features three different spots out-of-the-box; CarouselSpot, GridSpot, ListSpot
  • Static custom cell registrations for all Spotable objects. Write one view cell and use it across your application, when and where you want to use it.
  • Cell height caching, this improves performance as each cell has its height stored as a calculated value. on the view model.
  • Supports multiple cell types inside the same data source, no more ugly if-statements in your implementation;
  • Soft & hard updates to UI components.
  • Supports both views made programmatically and nib-based views. Spots handles this for you by using a cell registry.

Origin Story

We wrote a Medium article about how and why we built Spots. You can find it here: Hitting the sweet spot of inspiration


JSON works great as a common transport language, it is platform agnostic and it is something that developers are already using regularly when building application that fetch data from an external resource. Spots uses JSON internally to save a snapshot of the view state to disk, the only thing that you have to do is to give the Controller a cache key and call save whenever you have performed your update.

So what if I don't have a backend that supports Spots view models? Not to worry, you can set up Spots programmatically and still use all the other advantages of the framework.

View state caching

As mentioned above, Spots features a view state cache. Instead of saving all your data in a database somewhere and perform queries every time to initiate a view controller, we went with a different and much simpler approach. If a Controller has a cache key and you call save, internally it will encode all underlaying Spotable objects and its children into a JSON file and store that to disk. The uniqueness of the file comes from the cache key, think of this like your screen identifier. The next time you construct a Controller with that cache key, it will try to load that from disk and display it the exact same way as it was before saving. The main benefit here is that you don’t have to worry about your object changing by updating to future versions of Spots.

ListSpot, GridSpot, CarouselSpot also have support for view state caching because these components can be used separately without using Controller.

View state caching is optional but we encourage you to use it, as it renders the need to use a database as optional.

Live editing

As mentioned above, Spots internal view state cache uses JSON for saving the state to disk. To leverage even more from JSON, Spots has a built-in feature to live edit what you see on screen. If you compile Spots with the -DDEVMODE flag, Spots will monitor the current cache for any changes applied to the view cache. It will also print the current cache path to the console so that you easily grab the file url, open it in your favorite source code editor to play around your view and have it reload whenever you save the file.

Live editing only works when running your application in the Simulator.

See Installation for how to enable live editing using Cocoapods.

How does it work?

At the top level of Spots, you have the Controller which is the replacement for your view controller.

Inside of the Controller, you have a SpotsScrollView that handles the linear layout of the components that you add to your data source. It is also in charge of giving the user a unified scrolling experience. Scrolling is disabled on all underlaying components except for components that have horizontal scrolling (e.g CarouselSpot).

So how does scrolling work? Whenever a user scrolls, the SpotsScrollView computes the offset and size of its children. By using this technique you can easily create screens that contain lists, grids and carousels with a scrolling experience as smooth as proverbial butter. By dynamically changing the size and offset of the children, SpotsScrollView also ensures that reusable views are allocated and deallocated like you would expect them to. SpotsScrollView uses KVO on any view that gets added so if one component changes height or position, the entire layout will invalidate itself and redraw it like it was intended.

Controller uses one or more Spotable objects. Spotable is a protocol that all components use to make sure that all layout calculations can be performed. Spots comes with three different Spotable objects out-of-the-box. All Spotable objects are based around one core UI element.

ListSpot is an object that conforms to Listable, it has a ListAdapter that works as both the data source and delegate for the ListSpot. For iOS, Listable uses UITableView as its UI component, and NSTableView on macOS.

GridSpot is an object that conforms to Gridable, it uses a different adapter than ListSpot as it is based on collection views. The adapter used here is CollectionAdapter. On iOS and tvOS, Gridable uses UICollectionView as its UI component and NSCollectionView on macOS.

CarouselSpot is very similar to GridSpot, it shares the same CollectionAdapter, the main difference between them is that CarouselSpot has scrolling enabled and uses a process for laying its views out on screen.

What all Spotable objects have in common is that all of them use the same Component struct to represent themselves. Component has a kind property that maps to the UI component that should be used. By just changing the kind, you can transform a list into a grid as fast has you can type it and hit save.

They also share the same Item struct for its children. The child is a data container that includes the size of the view on screen and the remaining information to configure your view.

To add your own view to Spots, you need the view to conform to SpotConfigurable and inherit from the core class that your component is based on (UITableViewCell on ListSpot, UICollectionViewCell on CarouselSpot and GridSpot). SpotConfigurable requires you to implement one property and one method.

We don’t like to dictate the terms of how you build your views, if you prefer to build them using .nib files, you should be free to do so, and with Spots you can. The only thing that differs is how you register the view on the component.

var preferredViewSize: CGSize { get }

func configure(inout item: Item)

preferredViewSize is exactly what the name implies, it is the preferred size for the view when it should be rendered on screen. We used the prefix preferred as it might be different if the view has dynamic height.

Using different heights for different objects can be a hassle in iOS, tvOS and macOS, but not with Spots. To set a calculated height based on the Item content, you simply set the height back to the item when you are done calculating it in configure(inout item: Item).


func configure(inout item: Item) {
  textLabel.text = item.title
  item.size.height = textLabel.frame.size.height

Item is a struct, but because of the inout keyword in the method declaration it can perform mutation and pass that back to the data source. If you prefer the size to be static, you can simply not set the height and Spots will handle setting it for you based on the preferredViewSize.

When your view conforms to SpotConfigurable, you need to register it with a unique identifier for that view.

You register your view on the component that you want to display it in.

ListSpot.register(view: MyAwesomeView.self, identifier: “my-awesome-view”)

For nib-based views, you register them like this.

ListSpot.register(nib: UINib(nibName: "MyAwesomeView", bundle: NSBundle.mainBundle()), identifier: "my-awesome-view")

You can also register default views for your component, what it means is that it will be the fallback view for that view if the identifier cannot be resolved or the identifier is absent.

ListSpot.register(defaultView: MyAwesomeView.self)

As mentioned above, ListSpot is based on UITableView (and NSTableView in macOS).

By letting the data decide which views to use gives you the freedom of displaying anything anywhere, without cluttering your code with dirty if- or switch-statements that are hard to maintain and prone to introduce bugs.

Performing mutation

It is very common that you need to modify your data source and tell your UI component to either insert, update or delete depending on the action that you performed. This process can be cumbersome, so to help you out, Spots has some great convenience methods to help you with this process.

On Controller you have simple methods like reload(withAnimation, completion) that tells all the Spotable objects to reload.

You can reload Controller using a collection of Component’s. Internally it will perform a diffing process to pinpoint what changed, in this process it cascades down from component level to item level, and checks all the moving parts, to perform the most appropriate update operation depending on the change. At item level, it will check if the items size changed, if not it will scale down to only run the configure method on the view that was affected. This is what we call hard and soft updates, it will reduce the amount of blinking that you can normally see in iOS.

A Controller can also be reloaded using JSON. It behaves a bit differently than reloadIfNeeded(withComponents) as it will create new component and diff them towards each other to find out if something changed. If something changed, it will simply replace the old objects with the new ones.

The difference between reload and reloadIfNeeded methods is that they will only run if change is needed, just like the naming implies.

If you need more fine-grained control by pinpointing an individual spot, we got you covered on this as well. Controller has an update method that takes the spot index as its first argument, followed by an animation label to specify which animation to use when doing the update. The remaining arguments are one mutation closure where you get the Spotable object and can perform your updates, and finally one completion closure that will run when your update is performed both on the data source and the UI component. This method has a corresponding method called updateIfNeeded, which applies the update if needed.

You can also append prepend, insert, update or delete with a series to similar methods that are publicly available on Controller.

All methods take an Item as their first argument, the second is the index of the Spotable object that you want to update. Just like reload and update, it also has an animation label to give you control over what animation should be used. As an added bonus, these methods also work with multiple items, so instead of passing just one item, you can pass a collection of items that you want to append, prepend etc.


View models in the Cloud

let controller = Controller(json)
navigationController?.pushViewController(controller, animated: true)

The JSON data will be parsed into view model data and your view controller is ready to be presented, it is just that easy.

Programmatic approach

let myContacts = Component(title: "My contacts", items: [
  Item(title: "John Hyperseed"),
  Item(title: "Vadym Markov"),
  Item(title: "Ramon Gilabert Llop"),
  Item(title: "Khoa Pham"),
  Item(title: "Christoffer Winterkvist")
let listSpot = ListSpot(component: myContacts)
let controller = Controller(spots: [listSpot])

navigationController?.pushViewController(controller, animated: true)


The Controller inherits from UIViewController and NSViewController but it sports some core features that makes your everyday mundane tasks a thing of the past. Controller has four different delegates



public protocol SpotsDelegate: class {
  func spotDidSelectItem(spot: Spotable, item: Item)
  func spotsDidChange(spots: [Spotable])

spotDidSelectItem is triggered when a user taps on an item inside of a Spotable object. It returns both the spot and the item to add context to what UI element was touched.

spotsDidChange notifies the delegate when the internal .spots property changes.


public protocol SpotsRefreshDelegate: class {
  func spotsDidReload(refreshControl: UIRefreshControl, completion: (() -> Void)?)

spotsDidReload is triggered when a user pulls the SpotsScrollView offset above its initial bounds.


public protocol SpotsScrollDelegate: class {
  func spotDidReachBeginning(completion: Completion)
  func spotDidReachEnd(completion: (() -> Void)?)

spotDidReachBeginning notifies the delegate when the scrollview has reached the top. This has a default implementation and is rendered optional for anything that conform to SpotsScrollDelegate.

spotDidReachEnd is triggered when the user scrolls to the end of the SpotsScrollView, this can be used to implement infinite scrolling.


public protocol SpotsCarouselScrollDelegate: class {
  func spotDidEndScrolling(spot: Spotable, item: Item)

spotDidEndScrolling is triggered when a user ends scrolling in a carousel, it returns item that is being displayed and the spot to give you the context that you need.

The many faces of Spots

Because the framework can be used in a wide variety of ways, we have decided to include more than one example project. If you are feeling adventurous, you should take a peek at the Examples folder.

JSON structure

         "title":"Hyper iOS",
               "title":"John Hyperseed",
               "subtitle":"Build server",
               "image":"{image url}",
               "title":"Vadym Markov",
               "subtitle":"iOS Developer",
               "image":"{image url}",
               "title":"Ramon Gilabert Llop",
               "subtitle":"iOS Developer",
               "image":"{image url}",
               "title":"Khoa Pham",
               "subtitle":"iOS Developer",
               "image":"{image url}",
               "title":"Christoffer Winterkvist",
               "subtitle":"iOS Developer",
               "image":"{image url}",



  public struct Component: Mappable {
  public var index = 0
  public var title = ""
  public var kind = ""
  public var span: CGFloat = 0
  public var items = [Item]()
  public var size: CGSize?
  public var meta = [String : String]()
  • .index Calculated value to determine the index it has inside of the spot.
  • .title This is used as a title in table view view.
  • .kind Determines which spot should be used. carousel, list, grid are there by default but you can register your own.
  • .span Determines the amount of views that should fit on one row, by default it is set to zero and uses the default flow layout to render collection based views.
  • .size Calculated value based on the amount of items and their combined heights.
  • .meta Custom data that you are free to use as you like in your implementation.


  public struct Item: Mappable {
  public var index = 0
  public var title = ""
  public var subtitle = ""
  public var image = ""
  public var kind = ""
  public var action: String?
  public var size = CGSize(width: 0, height: 0)
  public var meta = [String : AnyObject]()
  • .index Calculated value to determine the index it has inside of the component.
  • .title The headline for your data, in a UITableViewCell it is normally used for textLabel.text but you are free to use it as you like.
  • .subtitle Same as for the title, in a UITableViewCell it is normally used for detailTextLabel.text.
  • .image Can be either a URL string or a local string, you can easily determine if it should use a local or remote asset in your view.
  • .kind Is used for the reuseIdentifier of your UITableViewCell or UICollectionViewCell.
  • .action Action identifier for you to parse and process when a user taps on a list item. We recommend Compass as centralized navigation system.
  • .size Can either inherit from the UITableViewCell/UICollectionViewCell, or be manually set by the height calculations inside of your view.
  • .meta This is used for extra data that you might need access to inside of your view, it can be a hex color, a unique identifer or additional images for your view.


Spots is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'Spots'

Spots is also available through Carthage. To install it, add the following to your Cartfile:

github "hyperoslo/Spots"

If you want to enable live editing for you debug target. Add the following to your Podfile:

target 'YOUR TARGET HERE' do
  post_install do |installer|
    puts("Update debug pod settings to speed up build time")
    Dir.glob(File.join("Pods", "**", "Pods*{debug,Private}.xcconfig")).each do |file|, 'a') { |f| f.puts "\nDEBUG_INFORMATION_FORMAT = dwarf" }
    installer.pods_project.targets.each do |target|
      if == 'Spots'
        target.build_configurations.each do |config|
          if == 'Debug'
            config.build_settings['OTHER_SWIFT_FLAGS'] = '-DDEBUG -DDEVMODE'
            config.build_settings['OTHER_SWIFT_FLAGS'] = ''


  • Brick Item comes from Brick.
  • Cache Used for Component and Item caching when initializing a Controller or Spotable object with a cache key.
  • Tailor To seamlessly map JSON to both Component and Item.


Hyper made this with ❤. If you’re using this library we probably want to hire you! Send us an email at


We would love you to contribute to Spots, check the CONTRIBUTING file for more info.



Spots is available under the MIT license. See the LICENSE file for more info.