Alex.k
85 lines
3.0 KiB
Swift
85 lines
3.0 KiB
Swift
//
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// CollectionViewStackFlowLayout.swift
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// NavigationStackDemo
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//
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// Created by Alex K. on 25/02/16.
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// Copyright © 2016 Alex K. All rights reserved.
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//
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import UIKit
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// MARK: CollectionViewStackFlowLayout
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class CollectionViewStackFlowLayout: UICollectionViewFlowLayout {
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let itemsCount: Int
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init(itemsCount: Int) {
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self.itemsCount = itemsCount
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super.init()
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}
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required init?(coder aDecoder: NSCoder) {
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fatalError("init(coder:) has not been implemented")
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}
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}
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extension CollectionViewStackFlowLayout {
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override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
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let items = NSArray (array: super.layoutAttributesForElementsInRect(rect)!, copyItems: true)
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var headerAttributes: UICollectionViewLayoutAttributes?
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items.enumerateObjectsUsingBlock { (object, idex, stop) -> Void in
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let attributes = object as! UICollectionViewLayoutAttributes
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if attributes.representedElementKind == UICollectionElementKindSectionHeader {
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headerAttributes = attributes
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}
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else {
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self.updateCellAttributes(attributes, headerAttributes: headerAttributes)
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}
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}
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return items as? [UICollectionViewLayoutAttributes]
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}
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func updateCellAttributes(attributes: UICollectionViewLayoutAttributes, headerAttributes: UICollectionViewLayoutAttributes?) {
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guard let collectionView = self.collectionView else {
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return;
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}
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let itemWidth = collectionView.bounds.size.width - collectionView.bounds.size.width * 0.2 // hack
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let maxScale = 0.8 - CGFloat(itemsCount - attributes.indexPath.row) / 50.0
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let minScale = 0.7 - CGFloat(itemsCount - attributes.indexPath.row) / 50.0
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let allWidth = itemWidth * CGFloat(itemsCount - 1)
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// scale
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var currentScale = (maxScale + minScale) - (minScale + collectionView.contentOffset.x / (allWidth / (maxScale - minScale)))
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currentScale = currentScale > maxScale ? maxScale : currentScale
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currentScale = currentScale < minScale ? minScale : currentScale
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attributes.transform = CGAffineTransformMakeScale(currentScale, currentScale)
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attributes.zIndex = attributes.indexPath.row
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//
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//
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//
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if attributes.indexPath.row == 0 {
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// attributes.frame = CGRect(origin: CGPoint(x: attributes.bounds.origin.x + collectionView.contentOffset.x / 4.0, y: attributes.frame.origin.y),
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// size: attributes.frame.size)
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// attributes.center = CGPoint(x: attributes.bounds.origin.x + collectionView.contentOffset.x / 4.0, y: attributes.center.y)
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// print(attributes.frame)
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// attributes.frame = CGRect(x: attributes.bounds.origin.x + collectionView.contentOffset.x / 4.0,
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// y: attributes.frame.origin.y, width: attributes.frame.size.width, height: attributes.frame.size.height)
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// print(attributes.frame)
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}
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}
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override func shouldInvalidateLayoutForBoundsChange(newBounds: CGRect) -> Bool {
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return true
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}
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}
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