Changed ChatLayoutDelegate and improved performance

Author: ekazaev

ChatLayout.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'ChatLayout'
-  s.version          = '0.3.0'
+  s.version          = '0.4.0'
   s.summary          = 'An alternative solution to MessageKit. It uses custom UICollectionViewLayout to provide you full control over the presentation.'
   s.swift_version    = '5.2'
 

ChatLayout/Classes/Core/ChatLayout.swift

@@ -135,7 +135,7 @@ public final class ChatLayout: UICollectionViewLayout {
         static let shouldInvalidateOnBoundsChange = InvalidationActions(rawValue: 1 << 0)
     }
 
-    private lazy var controller = StateController(collectionLayout: self)
+    private lazy var controller = StateController(layoutRepresentation: self)
 
     private var state: ModelState = .beforeUpdate
 
@@ -250,7 +250,7 @@ public final class ChatLayout: UICollectionViewLayout {
             for sectionIndex in 0..<collectionView.numberOfSections {
                 // Header
                 let header: ItemModel?
-                if delegate?.shouldPresentHeader(at: sectionIndex) == true {
+                if delegate?.shouldPresentHeader(self, at: sectionIndex) == true {
                     let headerIndexPath = IndexPath(item: 0, section: sectionIndex)
                     header = ItemModel(with: configuration(for: .header, at: headerIndexPath))
                 } else {
@@ -266,7 +266,7 @@ public final class ChatLayout: UICollectionViewLayout {
 
                 // Footer
                 let footer: ItemModel?
-                if delegate?.shouldPresentFooter(at: sectionIndex) == true {
+                if delegate?.shouldPresentFooter(self, at: sectionIndex) == true {
                     let footerIndexPath = IndexPath(item: 0, section: sectionIndex)
                     footer = ItemModel(with: configuration(for: .footer, at: footerIndexPath))
                 } else {
@@ -288,7 +288,7 @@ public final class ChatLayout: UICollectionViewLayout {
                 var section = controller.section(at: sectionIndex, at: state)
 
                 // Header
-                if delegate?.shouldPresentHeader(at: sectionIndex) == true {
+                if delegate?.shouldPresentHeader(self, at: sectionIndex) == true {
                     var header = section.header
                     header?.resetSize()
                     let headerIndexPath = IndexPath(item: 0, section: sectionIndex)
@@ -312,7 +312,7 @@ public final class ChatLayout: UICollectionViewLayout {
                 section.set(items: items)
 
                 // Footer
-                if delegate?.shouldPresentFooter(at: sectionIndex) == true {
+                if delegate?.shouldPresentFooter(self, at: sectionIndex) == true {
                     var footer = section.footer
                     let footerIndexPath = IndexPath(item: 0, section: sectionIndex)
                     footer?.alignment = alignment(for: .footer, at: footerIndexPath)
@@ -745,7 +745,7 @@ extension ChatLayout {
             return (estimated: estimatedItemSize, exact: nil)
         }
 
-        let itemSize = delegate.sizeForItem(of: element, at: indexPath)
+        let itemSize = delegate.sizeForItem(self, of: element, at: indexPath)
 
         switch itemSize {
         case .auto:
@@ -761,7 +761,7 @@ extension ChatLayout {
         guard let delegate = delegate else {
             return .full
         }
-        return delegate.alignmentForItem(of: element, at: indexPath)
+        return delegate.alignmentForItem(self, of: element, at: indexPath)
     }
 
     private var estimatedItemSize: CGSize {
@@ -798,6 +798,14 @@ extension ChatLayout: ChatLayoutRepresentation {
         return collectionView.numberOfItems(inSection: section)
     }
 
+    func shouldPresentHeader(at sectionIndex: Int) -> Bool {
+        return delegate?.shouldPresentHeader(self, at: sectionIndex) ?? false
+    }
+
+    func shouldPresentFooter(at sectionIndex: Int) -> Bool {
+        return delegate?.shouldPresentFooter(self, at: sectionIndex) ?? false
+    }
+
 }
 
 extension ChatLayout {

ChatLayout/Classes/Core/ChatLayoutDelegate.swift

@@ -14,43 +14,57 @@ import UIKit
 public protocol ChatLayoutDelegate: AnyObject {
 
     /// `ChatLayout` will call this method to ask if it should present the header in the current layout.
-    /// - Parameter sectionIndex: Index of the section.
-    func shouldPresentHeader(at sectionIndex: Int) -> Bool
+    /// - Parameters:
+    ///   - chatLayout: ChatLayout reference.
+    ///   - sectionIndex: Index of the section.
+    /// - Returns: `Bool`.
+    func shouldPresentHeader(_ chatLayout: ChatLayout, at sectionIndex: Int) -> Bool
 
     /// `ChatLayout` will call this method to ask if it should present the footer in the current layout.
-    /// - Parameter sectionIndex: Index of the section.
-    func shouldPresentFooter(at sectionIndex: Int) -> Bool
+    /// - Parameters:
+    ///   - chatLayout: ChatLayout reference.
+    ///   - sectionIndex: Index of the section.
+    /// - Returns: `Bool`.
+    func shouldPresentFooter(_ chatLayout: ChatLayout, at sectionIndex: Int) -> Bool
 
-    /// `ChatLayout` will call this method to ask what type of alignment the item should have.
+    /// `ChatLayout` will call this method to ask what size the item should have.
     /// - Parameters:
+    ///   - chatLayout: ChatLayout reference.
     ///   - kind: Type of element represented by `ItemKind`.
     ///   - indexPath: Index path of the item.
-    func alignmentForItem(of kind: ItemKind, at indexPath: IndexPath) -> ChatItemAlignment
+    /// - Returns: `ItemSize`.
+    func sizeForItem(_ chatLayout: ChatLayout, of kind: ItemKind, at indexPath: IndexPath) -> ItemSize
 
-    /// `ChatLayout` will call this method to ask what size the item should have.
+    /// `ChatLayout` will call this method to ask what type of alignment the item should have.
     /// - Parameters:
+    ///   - chatLayout: ChatLayout reference.
     ///   - kind: Type of element represented by `ItemKind`.
     ///   - indexPath: Index path of the item.
-    func sizeForItem(of kind: ItemKind, at indexPath: IndexPath) -> ItemSize
+    /// - Returns: `ChatItemAlignment`.
+    func alignmentForItem(_ chatLayout: ChatLayout, of kind: ItemKind, at indexPath: IndexPath) -> ChatItemAlignment
 
 }
 
 /// Default extension.
 public extension ChatLayoutDelegate {
 
-    func shouldPresentHeader(at sectionIndex: Int) -> Bool {
+    /// Default implementation returns: `false`.
+    func shouldPresentHeader(_ chatLayout: ChatLayout, at sectionIndex: Int) -> Bool {
         return false
     }
 
-    func shouldPresentFooter(at sectionIndex: Int) -> Bool {
+    /// Default implementation returns: `false`.
+    func shouldPresentFooter(_ chatLayout: ChatLayout, at sectionIndex: Int) -> Bool {
         return false
     }
 
-    func sizeForItem(of kind: ItemKind, at indexPath: IndexPath) -> ItemSize {
+    /// Default implementation returns: `ItemSize.auto`.
+    func sizeForItem(_ chatLayout: ChatLayout, of kind: ItemKind, at indexPath: IndexPath) -> ItemSize {
         return .auto
     }
 
-    func alignmentForItem(of kind: ItemKind, at indexPath: IndexPath) -> ChatItemAlignment {
+    /// Default implementation returns: `ChatItemAlignment.full`.
+    func alignmentForItem(_ chatLayout: ChatLayout, of kind: ItemKind, at indexPath: IndexPath) -> ChatItemAlignment {
         return .full
     }
 

ChatLayout/Classes/Core/Model/LayoutModel.swift

@@ -32,18 +32,7 @@ struct LayoutModel {
 
     // MARK: To use when its is important to make the correct insertion
 
-    mutating func setAndAssemble(section: SectionModel, sectionIndex: Int) {
-        guard sectionIndex < sections.count else {
-            assertionFailure("Internal inconsistency")
-            return
-        }
-        let oldSection = sections[sectionIndex]
-        sections[sectionIndex] = section
-        let heightDiff = sections[sectionIndex].height - oldSection.height
-        offsetEverything(below: sectionIndex, by: heightDiff)
-    }
-
-    mutating func setAndAssemble(header: ItemModel?, sectionIndex: Int) {
+    mutating func setAndAssemble(header: ItemModel, sectionIndex: Int) {
         guard sectionIndex < sections.count else {
             assertionFailure("Internal inconsistency")
             return
@@ -66,7 +55,7 @@ struct LayoutModel {
         offsetEverything(below: sectionIndex, by: heightDiff)
     }
 
-    mutating func setAndAssemble(footer: ItemModel?, sectionIndex: Int) {
+    mutating func setAndAssemble(footer: ItemModel, sectionIndex: Int) {
         guard sectionIndex < sections.count else {
             assertionFailure("Internal inconsistency")
             return

ChatLayout/Classes/Core/Model/SectionModel.swift

@@ -79,19 +79,14 @@ struct SectionModel {
 
     // MARK: To use when its is important to make the correct insertion
 
-    mutating func setAndAssemble(header: ItemModel?) {
-        guard let oldHeader = self.header,
-            let newHeader = header else {
-            if let header = header, self.header == nil {
-                offsetEverything(below: -1, by: header.height)
-            } else if let oldHeader = self.header, header == nil {
-                offsetEverything(below: -1, by: -oldHeader.height)
-            }
+    mutating func setAndAssemble(header: ItemModel) {
+        guard let oldHeader = self.header else {
             self.header = header
+            offsetEverything(below: -1, by: header.height)
             return
         }
-        self.header = newHeader
-        let heightDiff = newHeader.height - oldHeader.height
+        self.header = header
+        let heightDiff = header.height - oldHeader.height
         offsetEverything(below: -1, by: heightDiff)
     }
 
@@ -107,11 +102,7 @@ struct SectionModel {
         offsetEverything(below: index, by: heightDiff)
     }
 
-    mutating func setAndAssemble(footer: ItemModel?) {
-        guard let _ = self.footer, let _ = footer else {
-            self.footer = footer
-            return
-        }
+    mutating func setAndAssemble(footer: ItemModel) {
         self.footer = footer
     }