0.2.0

Author: Geri-Borbas

CHANGELOG.md

@@ -1,6 +1,13 @@
 #  CHANGELOG
 
 
+* Feature/Empty_Label_Support/0.2.0
+
+	+ Added `oldText` and `newText` parameters to `onTextChange` observer
+	+ Renamed `placeholder` to `cache`
+	+ Apply cached attributes (if any) in case text have just changed from empty on text change
+	+ More testbed cleanup
+
 * Feature/Empty_Label_Support/0.1.9
 
 	+ Cleaned up testbed views

UILabel_Typography_Extensions/Typography/UILabel+Observer.swift

@@ -30,6 +30,7 @@ import UIKit
 extension UILabel {
 
 	typealias TextObserver = Observer<UILabel, String?>
+	typealias TextChangeAction = (_ oldValue: String?, _ newValue: String?) -> Void
 
 	fileprivate struct Keys {
 		static var observer: UInt8 = 0
@@ -44,27 +45,27 @@ extension UILabel {
 		}
 	}
 
-	func onTextChange(onChange completion: @escaping () -> Void) {
+	func onTextChange(onChange completion: @escaping TextChangeAction) {
 		guard observer == nil else {
 			return
 		}
 
 		observer = TextObserver(
 			for: self,
 			keyPath: \.text,
-			onChange: { text in completion() }
+			onChange: { oldText, newText in completion(oldText ?? nil, newText ?? nil) }
 		)
 	}
 }
 
 
 class Observer<ObjectType: NSObject, ValueType>: NSObject {
 
-	typealias OnChangeAction = (_ value: ValueType?) -> Void
-	let onChange: OnChangeAction
+	typealias ChangeAction = (_ oldValue: ValueType?, _ newValue: ValueType?) -> Void
+	let onChange: ChangeAction
 	private var observer: NSKeyValueObservation?
 
-	init(for object: ObjectType, keyPath: KeyPath<ObjectType, ValueType>, onChange: @escaping OnChangeAction) {
+	init(for object: ObjectType, keyPath: KeyPath<ObjectType, ValueType>, onChange: @escaping ChangeAction) {
 		self.onChange = onChange
 		super.init()
 		observe(object, keyPath: keyPath)
@@ -75,7 +76,7 @@ class Observer<ObjectType: NSObject, ValueType>: NSObject {
 			keyPath,
 			options:  [.new, .old],
 			changeHandler: { [weak self] _, change in
-				self?.onChange(change.newValue ?? nil)
+				self?.onChange(change.oldValue, change.newValue)
 			}
 		)
 	}

UILabel_Typography_Extensions/Typography/UILabel+Typograpy.swift

@@ -25,15 +25,24 @@
 //
 
 import UIKit
+import SwiftUI
 
 
-extension UILabel: TypographyExtensions {
-	
-	/// Update attributed string layout due to (unknown) UIKit internals.
-	fileprivate func updateAttributedTextLayout() {
-		_ = self.attributedText
+extension Optional where Wrapped == String {
+	
+	var count: Int {
+		switch self {
+		case .none:
+			return 0
+		case .some(let wrapped):
+			return wrapped.count
+		}
 	}
-	
+}
+
+
+extension UILabel: TypographyExtensions {
+		
 	var paragraphStyle: NSParagraphStyle? {
 		getAttribute(.paragraphStyle)
 	}
@@ -48,29 +57,51 @@ extension UILabel: TypographyExtensions {
 				.paragraphStyle,
 				value: (paragraphStyle ?? NSParagraphStyle())
 					.mutable
+					.withProperty(textAlignment, for: \.alignment)
 					.withProperty(lineHeight, for: \.minimumLineHeight)
 					.withProperty(lineHeight, for: \.maximumLineHeight)
-					.withProperty(textAlignment, for: \.alignment)
 			)
-			onTextChange { [weak self] in
-				self?.updateAttributedTextLayout()
-            }
+			setupCache()
+		}
+	}
+	
+	func setupCache() {
+		onTextChange { [unowned self] oldText, newText in
+			
+			// Apply cached attributes (if any) in case text have just changed from empty.
+			if oldText.count == 0,
+			   newText.count > 0,
+			   let newText = newText {
+				self.attributedText = NSAttributedString(string: newText, attributes: cachedAttributes)
+			}
+			
+			// Update attributed string layout due to (unknown) UIKit internals.
+			_ = self.attributedText
 		}
 	}
 
 	public var letterSpacing: CGFloat? {
 		get { getAttribute(.kern) }
-		set { setAttribute(.kern, value: newValue) }
+		set {
+			setAttribute(.kern, value: newValue)
+			setupCache()
+		}
 	}
 
 	public var underline: NSUnderlineStyle? {
 		get { getAttribute(.underlineStyle) }
-		set { setAttribute(.underlineStyle, value: newValue) }
+		set {
+			setAttribute(.underlineStyle, value: newValue)
+			setupCache()
+		}
 	}
 
 	public var strikethrough: NSUnderlineStyle? {
 		get { getAttribute(.strikethroughStyle) }
-		set { setAttribute(.strikethroughStyle, value: newValue) }
+		set {
+			setAttribute(.strikethroughStyle, value: newValue)
+			setupCache()
+		}
 	}
 
 	public var leadingImage: Typography.Image? {
@@ -105,14 +136,16 @@ fileprivate extension NSAttributedString {
 }
 
 
+// MARK: Attributes
+
 fileprivate extension UILabel {
 
 	struct Keys {
 		static var placeholder: UInt8 = 0
 	}
 
 	/// An attributed string property to cache typography even when the label text is empty.
-	var placeholder: NSAttributedString {
+	var cache: NSAttributedString {
 		get {
 			objc_getAssociatedObject(self, &Keys.placeholder) as? NSAttributedString ?? NSAttributedString(string: "Placeholder")
 		}
@@ -121,26 +154,31 @@ fileprivate extension UILabel {
 		}
 	}
 
-	/// Attributes of `attributedText` (or the cached placeholder string if text is empty).
-	var attributes: [NSAttributedString.Key: Any] {
+	/// Attributes of `attributedText` (if any).
+	var attributes: [NSAttributedString.Key: Any]? {
 		get {
 			if let attributedText = attributedText,
 			   attributedText.length > 0 {
 				return attributedText.attributes(at: 0, effectiveRange: nil)
 			} else {
-				return placeholder.attributes(at: 0, effectiveRange: nil)
+				return nil
 			}
 		}
 	}
 
+	/// Attributes of `cache`.
+	var cachedAttributes: [NSAttributedString.Key: Any] {
+		cache.attributes(at: 0, effectiveRange: nil)
+	}
+	
 	func addAttribute(_ key: NSAttributedString.Key, value: Any) {
 		attributedText = attributedText?.stringByAddingAttribute(key, value: value)
-		placeholder = placeholder.stringByAddingAttribute(key, value: value)
+		cache = cache.stringByAddingAttribute(key, value: value)
 	}
 
 	func removeAttribute(_ key: NSAttributedString.Key) {
 		attributedText = attributedText?.stringByRemovingAttribute(key)
-		placeholder = placeholder.stringByRemovingAttribute(key)
+		cache = cache.stringByRemovingAttribute(key)
 	}
 }
 
@@ -151,14 +189,14 @@ extension UILabel {
 	fileprivate func getAttribute<AttributeType>(
 		_ key: NSAttributedString.Key
 	) -> AttributeType? where AttributeType: Any {
-		return attributes[key] as? AttributeType
+		return (attributes ?? cachedAttributes)[key] as? AttributeType
 	}
 
 	/// Get `OptionSet` attribute for the given key (if any).
 	fileprivate func getAttribute<AttributeType>(
 		_ key: NSAttributedString.Key
 	) -> AttributeType? where AttributeType: OptionSet {
-		if let attribute = attributes[key] as? AttributeType.RawValue {
+		if let attribute = (attributes ?? cachedAttributes)[key] as? AttributeType.RawValue {
 			return .init(rawValue: attribute)
 		} else {
 			return nil

UILabel_Typography_Extensions/View/AttributesViewController.swift

@@ -19,6 +19,15 @@ class AttributesViewController: UIViewController {
 		.vertical(spacing: 10)
 		.views(
 
+			UILabel()
+				.with {
+					$0.textColor = .label
+					$0.font = .preferredFont(forTextStyle: .headline)
+					$0.underline = .double
+					$0.showGrid = true
+				}
+				.with(text: "Underline"),
+			
 			UILabel()
 				.with(text: "Default")
 				.with {
@@ -80,7 +89,6 @@ class AttributesViewController: UIViewController {
 				},
 
 			UILabel()
-				.with(text: "🔠Letter Spacing / Alignment / Line Break Mode")
 				.with {
 					$0.textColor = .systemGray
 					$0.font = .preferredFont(forTextStyle: .body)
@@ -95,7 +103,8 @@ class AttributesViewController: UIViewController {
 				.withImages
 				.with {
 					self.label_4 = $0
-				},
+				}
+				.with(text: "🔠Letter Spacing / Alignment / Line Break Mode"),
 
 			UIView
 				.spacer

UILabel_Typography_Extensions/View/EmptyViewController.swift

@@ -22,19 +22,27 @@ class EmptyViewController: UIViewController {
 			$0.numberOfLines = 0
 			$0.showGrid = true
 			$0.lineHeight = CGFloat(87)
-			$0.underline = .double
+			$0.underline = .single
 			$0.textAlignment = .center
 
 			// Set text after.
 			$0.text = loremIpsum
 
 		}.inspect
 
-	var models: [(text: String, backgroundColor: UIColor)] = [
+	var models: [(text: String?, backgroundColor: UIColor)] = [
 		("Lorem ipsum dolor sit amet.", UIColor.systemBlue.withAlphaComponent(0.1)),
 		("Consectetur adipiscing elit.", UIColor.systemGreen.withAlphaComponent(0.1)),
 		("", UIColor.clear),
+		(nil, UIColor.clear),
 		("Sed do eiusmod tempor incididunt ut labore.", UIColor.systemOrange.withAlphaComponent(0.1)),
+		("Et dolore magna aliqua.", UIColor.systemIndigo.withAlphaComponent(0.1)),
+		("Et dolore magna aliqua.", UIColor.systemIndigo.withAlphaComponent(0.1)),
+		("Et dolore magna aliqua.", UIColor.systemIndigo.withAlphaComponent(0.1)),
+		("Et dolore magna aliqua.", UIColor.systemIndigo.withAlphaComponent(0.1)),
+		("", UIColor.clear),
+		("", UIColor.clear),
+		("Et dolore magna aliqua.", UIColor.systemIndigo.withAlphaComponent(0.1)),
 		("Et dolore magna aliqua.", UIColor.systemIndigo.withAlphaComponent(0.1))
 	]
 

UILabel_Typography_Extensions/View/LoremIpsumViewController.swift

@@ -17,7 +17,6 @@ class LoremIpsumViewController: UIViewController {
 		.views(
 
 			UILabel()
-				.with(text: loremIpsum)
 				.with {
 					$0.textColor = .label
 					$0.font = .preferredFont(forTextStyle: .headline)