Practical Dynamic Type, Part 3: Attributed Strings

dynamictype3-snippet1.swift

import Foundation
import UIKit

// MARK: - AttributedStringView
class AttributedStringView: UIView {

    /// `FontSetter` is a closure type used to recalculate the font size.
    typealias FontSetter = () -> UIFont

    /// A `UILabel` that will render the attributed string with Dynamic Type.
    lazy var display: UILabel = {
        let fontSetter1: FontSetter = { UIFont.customFont(weight: .bold, points: 18.0) }

        let string1 = NSAttributedString(
            string: "Jived fox nymph grabs quick waltz. ",
            attributes: [.font: fontSetter1()]
        )

        let fontSetter2: FontSetter = { UIFont.customFont(weight: .light, points: 8.0) }
        let string2 = NSAttributedString(
            string: "Glib jocks quiz nymph to vex dwarf. ",
            attributes: [.font: fontSetter2()]
        )

        let fontSetter3: FontSetter = { UIFont.customFont(NeutrafaceSlabTextFont.self,
                                                          weight: .demi,
                                                          points: 18.0,
                                                          maximumPointSize: 24.0) }
        let string3 = NSAttributedString(
            string: "Sphinx of black quartz, judge my vow. ",
            attributes: [.font: fontSetter3()]
        )

        let fontSetter4: FontSetter = { UIFont.customFont(weight: .heavy,
                                                          points: 48.0) }
        let string4 = NSAttributedString(
            string: "How vexingly quick daft zebras jump!",
            attributes: [.font: fontSetter4()]
        )

        var totalAttributedString = NSMutableAttributedString(attributedString: string1)
        totalAttributedString.append(string2)
        totalAttributedString.append(string3)
        totalAttributedString.append(string4)

        let label = UILabel(numberOfLines: 0)
        label.attributedText = totalAttributedString
        label.adjustsFontForContentSizeCategory = true

        return label
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)

        addSubview(display)
        NSLayoutConstraint.activate([
            display.topAnchor.constraint(equalTo: topAnchor),
            display.bottomAnchor.constraint(equalTo: bottomAnchor),
            display.leadingAnchor.constraint(equalTo: leadingAnchor),
            display.trailingAnchor.constraint(equalTo: trailingAnchor),
            ])
    }

    /// Although "required," we don't have to implement init(coder:) for now
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) not implemented for this article.")
    }
}