100 lines
5.8 KiB
Swift
100 lines
5.8 KiB
Swift
import UIKit
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/*
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Readable Auto Layout Constraints
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Usage:
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A.anchor =&= multiplier * B.anchor + constant | priority
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*/
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infix operator =&= : AdditionPrecedence
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infix operator =<= : AdditionPrecedence
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infix operator =>= : AdditionPrecedence
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//infix operator | : AdditionPrecedence
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/// Create and activate an `equal` constraint between left and right anchor. Format: `A.anchor =&= multiplier * B.anchor + constant | priority`
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@discardableResult func =&= <T>(l: NSLayoutAnchor<T>, r: NSLayoutAnchor<T>) -> NSLayoutConstraint { l.constraint(equalTo: r).on() }
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/// Create and activate a `lessThan` constraint between left and right anchor. Format: `A.anchor =<= multiplier * B.anchor + constant | priority`
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@discardableResult func =<= <T>(l: NSLayoutAnchor<T>, r: NSLayoutAnchor<T>) -> NSLayoutConstraint { l.constraint(lessThanOrEqualTo: r).on() }
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/// Create and activate a `greaterThan` constraint between left and right anchor. Format: `A.anchor =>= multiplier * B.anchor + constant | priority`
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@discardableResult func =>= <T>(l: NSLayoutAnchor<T>, r: NSLayoutAnchor<T>) -> NSLayoutConstraint { l.constraint(greaterThanOrEqualTo: r).on() }
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extension NSLayoutDimension { // higher precedence, so multiply first
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/// Create intermediate anchor multiplier result.
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static func *(l: CGFloat, r: NSLayoutDimension) -> AnchorMultiplier { .init(anchor: r, m: l) }
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}
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/// Intermediate `NSLayoutConstraint` anchor with multiplier supplement
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struct AnchorMultiplier {
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let anchor: NSLayoutDimension, m: CGFloat
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/// Create and activate an `equal` constraint between left and right anchor. Format: `A.anchor =&= multiplier * B.anchor + constant | priority`
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@discardableResult static func =&=(l: NSLayoutDimension, r: Self) -> NSLayoutConstraint { l.constraint(equalTo: r.anchor, multiplier: r.m).on() }
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/// Create and activate a `lessThan` constraint between left and right anchor. Format: `A.anchor =<= multiplier * B.anchor + constant | priority`
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@discardableResult static func =<=(l: NSLayoutDimension, r: Self) -> NSLayoutConstraint { l.constraint(lessThanOrEqualTo: r.anchor, multiplier: r.m).on() }
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/// Create and activate a `greaterThan` constraint between left and right anchor. Format: `A.anchor =>= multiplier * B.anchor + constant | priority`
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@discardableResult static func =>=(l: NSLayoutDimension, r: Self) -> NSLayoutConstraint { l.constraint(greaterThanOrEqualTo: r.anchor, multiplier: r.m).on() }
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}
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extension NSLayoutConstraint {
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/// Change `isActive`to `true` and return `self`
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func on() -> Self { isActive = true; return self }
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/// Change `constant`attribute and return `self`
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@discardableResult static func +(l: NSLayoutConstraint, r: CGFloat) -> NSLayoutConstraint { l.constant = r; return l }
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/// Change `constant` attribute and return `self`
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@discardableResult static func -(l: NSLayoutConstraint, r: CGFloat) -> NSLayoutConstraint { l.constant = -r; return l }
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/// Change `priority` attribute and return `self`
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@discardableResult static func |(l: NSLayoutConstraint, r: UILayoutPriority) -> NSLayoutConstraint { l.priority = r; return l }
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}
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extension NSLayoutDimension {
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/// Create and activate an `equal` constraint with constant value. Format: `A.anchor =&= constant | priority`
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@discardableResult static func =&= (l: NSLayoutDimension, r: CGFloat) -> NSLayoutConstraint { l.constraint(equalToConstant: r).on() }
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/// Create and activate a `lessThan` constraint with constant value. Format: `A.anchor =<= constant | priority`
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@discardableResult static func =<= (l: NSLayoutDimension, r: CGFloat) -> NSLayoutConstraint { l.constraint(lessThanOrEqualToConstant: r).on() }
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/// Create and activate a `greaterThan` constraint with constant value. Format: `A.anchor =>= constant | priority`
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@discardableResult static func =>= (l: NSLayoutDimension, r: CGFloat) -> NSLayoutConstraint { l.constraint(greaterThanOrEqualToConstant: r).on() }
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}
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/*
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UIView extension to generate multiple constraints at once
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Usage:
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child.anchor([.width, .height], to: parent) | .defaultLow
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*/
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extension UIView {
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/// Edges that need the relation to flip arguments. For these we need to inverse the constant value and relation.
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private static let inverseItem: [NSLayoutConstraint.Attribute] = [.right, .bottom, .trailing, .lastBaseline, .rightMargin, .bottomMargin, .trailingMargin]
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/// Create and active constraints for provided edges. Constraints will anchor the same edge on both `self` and `other`.
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/// - Note: Will set `translatesAutoresizingMaskIntoConstraints = false`
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/// - Parameters:
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/// - edges: List of constraint attributes, e.g. `[.top, .bottom, .left, .right]`
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/// - other: Instance to bind to, e.g. `UIView` or `UILayoutGuide`
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/// - margin: Used as constant value. Multiplier will always be `1.0`. If you need to change the multiplier, use single constraints instead. (Default: `0`)
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/// - rel: Constraint relation. (Default: `.equal`)
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/// - Returns: List of created and active constraints
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@discardableResult func anchor(_ edges: [NSLayoutConstraint.Attribute], to other: Any, margin: CGFloat = 0, if rel: NSLayoutConstraint.Relation = .equal) -> [NSLayoutConstraint] {
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translatesAutoresizingMaskIntoConstraints = false
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return edges.map {
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let (A, B) = UIView.inverseItem.contains($0) ? (other, self) : (self, other)
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return NSLayoutConstraint(item: A, attribute: $0, relatedBy: rel, toItem: B, attribute: $0, multiplier: 1, constant: margin).on()
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}
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}
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/// Sets the priority with which a view resists being made smaller and larger than its intrinsic size.
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func constrainHuggingCompression(_ axis: NSLayoutConstraint.Axis, _ priotity: UILayoutPriority) {
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setContentHuggingPriority(priotity, for: axis)
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setContentCompressionResistancePriority(priotity, for: axis)
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}
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}
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extension Array where Element: NSLayoutConstraint {
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/// set `priority` on all elements and return same list
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@discardableResult static func |(l: Self, r: UILayoutPriority) -> Self {
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for x in l { x.priority = r }
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return l
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}
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}
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