Blueprint greatly simplifies the task of building and updating views as application state changes.

let view = BlueprintView(element: Label(text: "Hello from Blueprint!"))

Blueprint provides an architecture that allows you to:

• Declaratively define a UI hierarchy as pure values (Swift structs and enums).
• Display that hierarchy within your application.
• Update that hierarchy as application state changes (including animated transitions).

Use Blueprint any time you want to display a view hierarchy, but don't want to manage view lifecycle (hint: managing view lifecycle is a large portion of most conventional UIKit code). There are times when you want to manage view lifecycle (complex animations and transitions are a good example), and for these cases you may want to stick with a conventional approach.

Blueprint is not a replacement for UIKit! From the beginning, Blueprint has been designed as a compliment to all of the powerful tools that come with the platform. You can use Blueprint to manage the display of a single view controller, or of a single view representing a small part of the screen. Likewise, it's straightforward to host standard views and controls within a blueprint hierarchy, always leaving you with an escape hatch.

They serve similar purposes, and SwiftUI has heavily influenced Blueprint's API. However, Blueprint predates SwiftUI, and works a bit differently. You can host a BlueprintView in SwiftUI to embed Blueprint within SwiftUI, and you can also use the provided ElementView to create Xcode previews of Blueprint. Because SwiftUI is hosted by a UIViewController, and Blueprint is hosted in a UIView, we don't provide a way to embed SwiftUI within Blueprint.

If you are developing your own package, be sure that Blueprint is included in dependencies in Package.swift:

dependencies: [
    .package(url: "https://github.com/square/Blueprint", from: "5.1.0")
]

In Xcode 11+, add Blueprint directly as a dependency to your project with File > Swift Packages > Add Package Dependency.... Provide the git URL when prompted: [email protected]:square/Blueprint.git.

Two modules are provided:

• BlueprintUI contains the core architecture and layout types.
• BlueprintUICommonControls includes elements representing some common UIKit views and controls.

API documentation is available at square.github.io/Blueprint

1. Hello, World

2. The Element Hierarchy

3. Building Custom Elements

4. Layout

1. Element

2. BlueprintView

3. ViewDescription

4. Transitions

Tutorial setup instructions

1. Using Blueprint in a View Controller

2. Building a receipt layout with Blueprint

This project uses Mise and Tuist to generate a project for local development. Follow the steps below for the recommended setup for zsh.

# install mise
brew install mise
# add mise activation line to your zshrc
echo 'eval "$(mise activate zsh)"' >> ~/.zshrc
# load mise into your shell
source ~/.zshrc
# tell mise to trust Blueprint's config file
mise trust
# install dependencies
mise install

# only necessary for first setup or after changing dependencies
tuist install --path SampleApp
# generates and opens the Xcode project
tuist generate --path SampleApp

Copyright 2019 Square, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.