Rootstrap Blog

Implement elegant forms fast with RSFormView in Swift

Germán Stábile is an iOS developer on the Rootstrap team who writes about the challenges faced during iOS development. You can also follow Germán on LinkedIn

Note: this post is meant to discuss motivations and implementation of RSFormView, if you are interested in a tutorial on how to integrate please visit RSFormView Readme or the next article.


When I first tried React-Native for a short, form-based project, I discovered the extremely useful redux-form library. “It would be great to have this kind of library for iOS development” I thought. After I finished that project, I moved back to iOS native programming for another project–yay!

A few glances at the beautiful wireframes the design team provided and I see at least five forms for data entry. Then I thought, “It might be fun and useful to develop a form component with such a beautiful design, by default!”.

As an iOS developer, I’ve seen and worked with lots of different form implementations. Some repeated too much code. And the ones with a more componentized solution were buggy, hard to extend or accomplish the intended design.

I wanted to avoid these issues and implement something we could use in different projects. Although, given the time constraints I knew I couldn’t build something as configurable as redux-form.

However, with the beautiful design I was handed over, and making fonts, colors, and margins configurable, we could put together a really helpful library. That we can always extend in the future.

Development on that project was very smooth having implemented this component beforehand. I was able to finish any form based screen in a few minutes and with very few lines of code. I was so happy with the results that I wanted to use the extra time in my hands and share the goods with the open source community.

What is RSFormView?

RSFormView is a library that allows you to create data entry forms in a few minutes with a modern look and feel based on material design 2, that you can also configure setting your custom colors, fonts, and margins or even adding your own custom views.


What can RSFormView do?

  • Supports different data entry options out-of-the-box: regular text fields, password text fields, date pickers, options pickers, etc.
  • Provides default validation for each text field type. Default validation can be overridden with any of the available validation types or your custom validation.
  • Configuration is easy. You choose if the FormView is scrollable or not. You choose your own fonts, colors, and margins for each text field state: editing, valid, and invalid.
  • The FormView makes a callback to its delegate whenever a change is made. Then you can update any view dependant on the data entered. An example is to enable or disable a submit button.
  • You can easily collect the entered data by iterating the items array of your FormViewModel.
  • You can manually mark items as invalid, which is useful for back-end validation.
  • TextFieldView is an independent component, you can use it without a RSFormView.
  • Dark mode configuration can be set with a single line of code.
  • Ability to perform matching validation: useful for password/confirm password fields.
  • Adding custom views to have your own look and feel.

What needs improvement?

  • Adding more out-of-the-box field types (we are planning to do this gradually as we identify more needs).
  • Better support for long error messages.
  • Support for Carthage.
  • Support for Swift Package Manager.

How is it implemented?

FormView is a custom view with a single UITableView embedded. The table view is populated with three out-of-the-box cells: TextFieldCellTwoTextFieldsCellFormTextCell.

What type of cell is going to be displayed is determined by your implementation of the FormViewModel protocol. The protocol requires that you hold a FormItem array.

We provide some FormItem subclasses by default: TextFieldCellItemTwoTextFieldCellItem and TextCellItem. A TextFieldCellItem will be rendered as TextFieldCellTwoTextFieldCellItem will be rendered as a TwoTextFieldsCellTextCellItem with an NSAttributedString will be render as FormTextCell you can use as a header, beside the NSAttributedString attributes you can further customize it by setting a ConstraintsConfigurator.

TextFieldCells hold a TextFieldView that is going to update its state according to the text entered and the validation you have set in the related FormField, validations will be done real-time (as the user types). The delegate will be notified every time an entry is made, so you can update any dependant view as needed.

To describe the validation, field type, placeholder, title and more of your text fields you set a FormField to your TextFieldCellItems .

See the RSFormView README for usage examples and guidance: In that repo, there’s also an example app using RSFormView. Feel free to leave your feedback and create issues to request improvements or additions.

If you’re interested in a tutorial showcasing some of the functionalities continue reading.

Thanks so much for reading this blog! I hope you find the library useful!


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