An expressive and extensible DSL for creating Auto Layout constraints and defining declarative layouts.
- Availability and Requirements
- Creating Constraints
- View builder DSL
UIViewandUILayoutGuide- Autoresizing Mask
- Debugging Constraints
- License
- Available as a Swift Package.
- Requires Xcode 12 or higher.
- Supports iOS 13+, and tvOS 13+.
// Creating inactive constraints (save and activate/manipulate later)
let constraints = view.makeConstraints {
Center()
Size(width: 100, height: 100)
}// Creating active constraints
view.applyConstraints {
Center()
Size(width: 100, height: 100)
}Create UIKit layouts with a view builder DSL.
UIStackView.vertical(spacing: 10) {
image
.overlay {
badge.constraints {
AlignEdges([.bottom, .trailing], insets: 8)
Size(width: 20, height: 20)
}
}
.constraints {
AspectRatio(3 / 2)
}
UIStackView.vertical(spacing: 10) {
titleLabel
summaryLabel
.spacingAfter(20)
UIStackView.horizontal {
timeLabel
HorizontalSpacer()
playButton
}
}
.padding(.horizontal, insets: 8)
VerticalSpacer()
}Generates this layout:
makeConstraints and applyConstraints operate on both UIView and UILayoutGuide. All constraints that are setup up in relation to other items may also be either UIView or UILayoutGuide.
button.applyConstraints {
Center(in: view.safeAreaLayoutGuide), // relating to a `UILayoutGuide`
Size(to: otherButton) // relating to a `UIView`
}Constraints that are related to another item default to the receiver’s parent view. Therefore, the following two examples are identical:
// Preferred
button.applyConstraints {
Center()
}// Not-preferred
button.applyConstraints {
Center(in: button.superview)
}Layout sets translatesAutoresizingMaskIntoConstraints to false on the receiver of the makeConstraints and applyConstraints calls.
Layout automatically adds debug identifiers to all constraints that include the file, and line number of where the constraint was created.
You may also set custom identifiers:
button.applyConstraints {
Center() <- "my first custom identifier"
}This code and tool is under the MIT License. See LICENSE file in this repository.