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================================================
FILE: Example/StickyHeaderFlowLayout.xcodeproj/project.xcworkspace/contents.xcworkspacedata
================================================
================================================
FILE: Example/StickyHeaderFlowLayout.xcodeproj/xcshareddata/xcschemes/Example.xcscheme
================================================
================================================
FILE: Example/StickyHeaderFlowLayout.xcworkspace/contents.xcworkspacedata
================================================
================================================
FILE: Example/StickyHeaderFlowLayout.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
================================================
IDEDidComputeMac32BitWarning
================================================
FILE: LICENSE
================================================
MIT License
Copyright (c) 2018 Timur Bernikowich
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
================================================
FILE: README.md
================================================
StickyHeaderFlowLayout
Sticky headers for UICollectionView written in pure Swift
Based on [CSStickyHeaderFlowLayout](https://github.com/CSStickyHeaderFlowLayout/CSStickyHeaderFlowLayout). `StickyHeaderFlowLayout` makes it easy to create sticky headers in `UICollectionView`.
## Integration
#### CocoaPods
You can use [CocoaPods](http://cocoapods.org/) to install `StickyHeaderFlowLayout` by adding it to your `Podfile`:
```ruby
platform :ios, '9.0'
target 'MyApp' do
pod 'StickyHeaderFlowLayout'
end
```
#### Manually
To use this library in your project manually you may:
Just drag `StickyHeaderFlowLayout.swift` and `StickyHeaderFlowLayoutAttributes.swift` to the project tree
## Usage
#### Sample project
Repository contains small sample project which shows basic integration.
#### Basic idea
1. Create layout and collection view
```swift
let layout = StickyHeaderFlowLayout()
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
```
2. Setup sticky header
```swift
collectionView.register(CollectionParallaxHeader.self, forSupplementaryViewOfKind: StickyHeaderFlowLayout.parallaxHeaderIdentifier, withReuseIdentifier: "parallaxHeader")
layout.parallaxHeaderReferenceSize = CGSize(width: view.frame.size.width, height: 200)
layout.parallaxHeaderMinimumReferenceSize = CGSize(width: view.frame.size.width, height: 160)
```
3. Return correct view in `viewForSupplementaryElementOfKind` function
```swift
override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
if kind == StickyHeaderFlowLayout.parallaxHeaderIdentifier {
return collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "parallaxHeader", for: indexPath)
}
// Other views.
...
}
```
## License
`StickyHeaderFlowLayout` is released under the MIT license. See `LICENSE` for details.
================================================
FILE: StickyHeaderFlowLayout/Assets/.gitkeep
================================================
================================================
FILE: StickyHeaderFlowLayout/Classes/.gitkeep
================================================
================================================
FILE: StickyHeaderFlowLayout/Classes/StickyHeaderFlowLayout.swift
================================================
//
// Created by Tsimur Bernikovich on 12/6/18.
// Copyright © 2018 Tsimur Bernikovich. All rights reserved.
//
import UIKit
open class StickyHeaderFlowLayout: UICollectionViewFlowLayout {
open class var parallaxHeaderIdentifier: String {
return "StickyHeaderParallexHeader"
}
private static let headerZIndex = 1024
open var parallaxHeaderReferenceSize: CGSize = .zero
open var parallaxHeaderMinimumReferenceSize: CGSize = .zero {
didSet {
invalidateLayout()
}
}
open var parallaxHeaderAlwaysOnTop = false
open var disableStickyHeaders = false
open var disableStretching = false
open override func prepare() {
super.prepare()
}
open override func initialLayoutAttributesForAppearingSupplementaryElement(ofKind elementKind: String, at elementIndexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
let attributes = super.initialLayoutAttributesForAppearingSupplementaryElement(ofKind: elementKind, at: elementIndexPath)
if elementKind == type(of: self).parallaxHeaderIdentifier {
// Sticky header do not need to offset.
return nil
} else {
if var frame = attributes?.frame {
frame.origin.y = parallaxHeaderReferenceSize.height
attributes?.frame = frame
}
}
return attributes
}
open override func finalLayoutAttributesForDisappearingSupplementaryElement(ofKind elementKind: String, at elementIndexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
if elementKind == type(of: self).parallaxHeaderIdentifier {
let attribute = layoutAttributesForSupplementaryView(ofKind: elementKind, at: elementIndexPath)
if let attribute = attribute as? StickyHeaderFlowLayoutAttributes {
updateParallaxHeaderAttribute(attribute)
}
return attribute
} else {
super.finalLayoutAttributesForDisappearingSupplementaryElement(ofKind: elementKind, at: elementIndexPath)
}
return nil
}
open override func layoutAttributesForSupplementaryView(ofKind elementKind: String, at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
var attrubutes = super.layoutAttributesForSupplementaryView(ofKind: elementKind, at: indexPath)
if attrubutes == nil && elementKind == type(of: self).parallaxHeaderIdentifier {
attrubutes = StickyHeaderFlowLayoutAttributes(forSupplementaryViewOfKind: elementKind, with: indexPath)
}
return attrubutes
}
open override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
guard collectionView?.dataSource != nil else {
return nil
}
// The rect should compensate the header size
var adjustedRect = rect
adjustedRect.origin.y -= self.parallaxHeaderReferenceSize.height
var allItems: [UICollectionViewLayoutAttributes] = []
// Perform a deep copy of the attributes returned from super.
if let originalAttributes = super.layoutAttributesForElements(in: adjustedRect) {
allItems = originalAttributes.compactMap {
$0.copy() as? UICollectionViewLayoutAttributes
}
}
var headers: [Int: UICollectionViewLayoutAttributes] = [:]
var lastCells: [Int: UICollectionViewLayoutAttributes] = [:]
var visibleParallaxHeader = false
for item in allItems {
let attributes = item
var frame = attributes.frame
frame.origin.y += parallaxHeaderReferenceSize.height
attributes.frame = frame
let indexPath = attributes.indexPath
let isHeader = attributes.representedElementKind == UICollectionView.elementKindSectionHeader
let isFooter = attributes.representedElementKind == UICollectionView.elementKindSectionFooter
if isHeader {
headers[indexPath.section] = attributes
} else if isFooter {
// Not implemeneted.
} else {
// Get the bottom most cell of that section.
if let currentAttribute = lastCells[indexPath.section] {
if indexPath.row > currentAttribute.indexPath.row {
lastCells[indexPath.section] = attributes
}
} else {
lastCells[indexPath.section] = attributes
}
if indexPath.item == 0 && indexPath.section == 0 {
visibleParallaxHeader = true
}
}
if isHeader {
attributes.zIndex = type(of: self).headerZIndex
} else {
// For iOS 7.0, the cell zIndex should be above sticky section header.
attributes.zIndex = 1
}
}
if rect.minY <= 0 {
visibleParallaxHeader = true
}
if parallaxHeaderAlwaysOnTop {
visibleParallaxHeader = true
}
// Create the attributes for the Parallex header.
if visibleParallaxHeader && parallaxHeaderReferenceSize != .zero {
let currentAttribute = StickyHeaderFlowLayoutAttributes(forSupplementaryViewOfKind: type(of: self).parallaxHeaderIdentifier, with: IndexPath(index: 0))
updateParallaxHeaderAttribute(currentAttribute)
allItems.append(currentAttribute)
}
if !disableStickyHeaders {
lastCells.forEach {
let indexPath = $0.value.indexPath
let indexPathKey = indexPath.section
if let header = headers[indexPathKey] {
if header.frame.size != .zero {
updateHeaderAttributes(header, lastCellAttributes: $0.value)
}
} else if let header = layoutAttributesForSupplementaryView(ofKind: UICollectionView.elementKindSectionHeader, at: IndexPath(item: 0, section: indexPath.section)) {
if header.frame.size != .zero {
allItems.append(header)
}
}
}
}
return allItems
}
open override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
let attributes = super.layoutAttributesForItem(at: indexPath)?.copy() as? UICollectionViewLayoutAttributes
if var frame = attributes?.frame {
frame.origin.y += parallaxHeaderReferenceSize.height
attributes?.frame = frame
}
return attributes
}
open override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
return true
}
open override class var layoutAttributesClass: AnyClass {
return StickyHeaderFlowLayoutAttributes.self
}
private func updateHeaderAttributes(_ attributes: UICollectionViewLayoutAttributes, lastCellAttributes: UICollectionViewLayoutAttributes) {
guard let collectionView = collectionView else {
return
}
let currentBounds = collectionView.bounds
attributes.zIndex = type(of: self).headerZIndex
attributes.isHidden = false
var origin = attributes.frame.origin
let sectionMaxY = lastCellAttributes.frame.maxY - attributes.frame.size.height
var y = currentBounds.maxY - currentBounds.size.height + collectionView.contentInset.top
if parallaxHeaderAlwaysOnTop {
y += parallaxHeaderMinimumReferenceSize.height
}
origin.y = min(max(y, attributes.frame.origin.y), sectionMaxY)
attributes.frame = CGRect(origin: origin, size: attributes.frame.size)
}
private func updateParallaxHeaderAttribute(_ currentAttribute: StickyHeaderFlowLayoutAttributes) {
guard let collectionView = collectionView else {
return
}
var frame = currentAttribute.frame
frame.size = parallaxHeaderReferenceSize
let bounds = collectionView.bounds
let maxY = frame.maxY
// Make sure the frame won't be negative values.
var y = min(maxY - parallaxHeaderMinimumReferenceSize.height, bounds.origin.y + collectionView.contentInset.top)
let height = max(0, -y + maxY)
let maxHeight = parallaxHeaderReferenceSize.height
let minHeight = parallaxHeaderMinimumReferenceSize.height
let progressiveness = (height - minHeight) / (maxHeight - minHeight)
currentAttribute.progressiveness = progressiveness
// If zIndex < 0 would prevents tap from recognized right under navigation bar.
currentAttribute.zIndex = 0
// When parallaxHeaderAlwaysOnTop is enabled, we will check when we should update the y position.
if parallaxHeaderAlwaysOnTop && height <= parallaxHeaderMinimumReferenceSize.height {
let insetTop = collectionView.contentInset.top
// Always stick to top but under the nav bar.
y = collectionView.contentOffset.y + insetTop
currentAttribute.zIndex = 2000
}
let normalizedHeight = disableStretching && height > maxHeight ? maxHeight : height
currentAttribute.frame = CGRect(x: frame.origin.x, y: y, width: frame.size.width, height: normalizedHeight)
}
}
extension StickyHeaderFlowLayoutAttributes {
override internal var debugDescription: String {
let indexPathString = "\(indexPath.section) \(indexPath.item)"
return " indexPath: \(indexPathString) zIndex: \(zIndex) valid: \(isValid) kind: \(representedElementKind ?? "cell")"
}
fileprivate var isValid: Bool {
switch representedElementCategory {
case .cell:
if zIndex != 1 {
return false
}
return true
case .supplementaryView:
if representedElementKind == StickyHeaderFlowLayout.parallaxHeaderIdentifier {
return true
} else if zIndex < 1024 {
return false
}
return true
default:
return true
}
}
}
private extension StickyHeaderFlowLayout {
func debugLayoutAttributes(_ layoutAttributes: [StickyHeaderFlowLayoutAttributes]) {
var hasInvalid = false
layoutAttributes.forEach {
if !$0.isValid {
hasInvalid = true
}
}
if hasInvalid {
print("StickyHeaderFlowLayout: \(layoutAttributes)")
}
}
}
================================================
FILE: StickyHeaderFlowLayout/Classes/StickyHeaderFlowLayoutAttributes.swift
================================================
//
// Created by Tsimur Bernikovich on 12/6/18.
// Copyright © 2018 Tsimur Bernikovich. All rights reserved.
//
import UIKit
class StickyHeaderFlowLayoutAttributes: UICollectionViewLayoutAttributes {
var progressiveness: CGFloat = 0
override func copy(with zone: NSZone? = nil) -> Any {
let copy = super.copy(with: zone)
if let copy = copy as? StickyHeaderFlowLayoutAttributes {
copy.progressiveness = progressiveness
}
return copy
}
override var zIndex: Int {
didSet {
// Fixes: Section header go behind cell when insert via performBatchUpdates #68
// https://github.com/jamztang/CSStickyHeaderFlowLayout/issues/68#issuecomment-108678022
// Reference: UICollectionView setLayout:animated: not preserving zIndex
// http://stackoverflow.com/questions/12659301/uicollectionview-setlayoutanimated-not-preserving-zindex
// originally our solution is to translate the section header above the original z position,
// however, scroll indicator will be covered by those cells and section header if z position is >= 1
// so instead we translate the original cell to be -1, and make sure the cell are hit test proven.
transform3D = CATransform3DMakeTranslation(0, 0, zIndex == 1 ? -1 : 0);
}
}
}
================================================
FILE: StickyHeaderFlowLayout.podspec
================================================
Pod::Spec.new do |spec|
spec.name = "StickyHeaderFlowLayout"
spec.version = "0.9.4"
spec.summary = "Sticky headers for UICollectionView written in pure Swift (based on CSStickyHeaderFlowLayout)"
spec.homepage = "https://github.com/bernikovich/StickyHeaderFlowLayout"
spec.license = { :type => "MIT", :file => "LICENSE" }
spec.author = { "Timur Bernikovich" => "bernikowich@icloud.com" }
spec.platform = :ios, "9.0"
spec.swift_version = "5.0"
spec.framework = "UIKit"
spec.source = { :git => "https://github.com/bernikovich/StickyHeaderFlowLayout.git", :tag => spec.version.to_s }
spec.source_files = "StickyHeaderFlowLayout/Classes/**/*.swift"
spec.module_name = "StickyHeaderFlowLayout"
end