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Merge pull request #29 from diegosanchezr/master 

Fixes scrollToBottom when typing very fast
This commit is contained in:
Diego Sánchez 2016-02-01 11:43:04 +00:00
parent 2cdbdc9063 148b64c996
commit 99b6d7ec5e
2 changed files with 22 additions and 7 deletions
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24
Chatto/Source/ChatController/ChatViewController+Scrolling.swift
View File

@ -29,6 +29,10 @@ public enum CellVerticalEdge {
case Bottom
}
extension CGFloat {
static let bma_epsilon: CGFloat = 0.001
}
extension ChatViewController {
public func isScrolledAtBottom() -> Bool {
@ -56,13 +60,13 @@ extension ChatViewController {
}
public func isIndexPathVisible(indexPath: NSIndexPath, atEdge edge: CellVerticalEdge) -> Bool {
if let attributes = self.collectionView.layoutAttributesForItemAtIndexPath(indexPath) {
if let attributes = self.collectionView.collectionViewLayout.layoutAttributesForItemAtIndexPath(indexPath) {
let visibleRect = self.visibleRect()
let intersection = visibleRect.intersect(attributes.frame)
if edge == .Top {
return intersection.minY == attributes.frame.minY
return CGFloat.abs(intersection.minY - attributes.frame.minY) < CGFloat.bma_epsilon
} else {
return intersection.maxY == attributes.frame.maxY
return CGFloat.abs(intersection.maxY - attributes.frame.maxY) < CGFloat.bma_epsilon
}
}
return false
@ -71,14 +75,24 @@ extension ChatViewController {
public func visibleRect() -> CGRect {
let contentInset = self.collectionView.contentInset
let collectionViewBounds = self.collectionView.bounds
return CGRect(x: CGFloat(0), y: self.collectionView.contentOffset.y + contentInset.top, width: collectionViewBounds.width, height: min(self.collectionView.contentSize.height, collectionViewBounds.height - contentInset.top - contentInset.bottom))
let contentSize = self.collectionView.collectionViewLayout.collectionViewContentSize()
return CGRect(x: CGFloat(0), y: self.collectionView.contentOffset.y + contentInset.top, width: collectionViewBounds.width, height: min(contentSize.height, collectionViewBounds.height - contentInset.top - contentInset.bottom))
}
public func scrollToBottom(animated animated: Bool) {
// Note that we don't rely on collectionView's contentSize. This is because it won't be valid after performBatchUpdates or reloadData
// After reload data, collectionViewLayout.collectionViewContentSize won't be even valid, so you may want to refresh the layout manually
let offsetY = max(-self.collectionView.contentInset.top, self.collectionView.collectionViewLayout.collectionViewContentSize().height - self.collectionView.bounds.height + self.collectionView.contentInset.bottom)
self.collectionView.setContentOffset(CGPoint(x: 0, y: offsetY), animated: animated)
// Don't use setContentOffset(:animated). If animated, contentOffset property will be updated along with the animation for each frame update
// If a message is inserted while scrolling is happening (as in very fast typing), we want to take the "final" content offset (not the "real time" one) to check if we should scroll to bottom again
if animated {
UIView.animateWithDuration(self.constants.updatesAnimationDuration, animations: { () -> Void in
self.collectionView.contentOffset = CGPoint(x: 0, y: offsetY)
})
} else {
self.collectionView.contentOffset = CGPoint(x: 0, y: offsetY)
}
}
public func scrollToPreservePosition(oldRefRect oldRefRect: CGRect?, newRefRect: CGRect?) {

5
Chatto/Source/ChatController/ChatViewController.swift
View File

@ -159,9 +159,10 @@ public class ChatViewController: UIViewController, UICollectionViewDataSource, U
let newInsetBottom = self.constants.defaultContentInsets.bottom + inputHeightWithKeyboard
let insetBottomDiff = newInsetBottom - self.collectionView.contentInset.bottom
let allContentFits = self.collectionView.bounds.height - newInsetBottom - (self.collectionView.contentSize.height + self.collectionView.contentInset.top) >= 0
let contentSize = self.collectionView.collectionViewLayout.collectionViewContentSize()
let allContentFits = self.collectionView.bounds.height - newInsetBottom - (contentSize.height + self.collectionView.contentInset.top) >= 0
let currentDistanceToBottomInset = max(0, self.collectionView.bounds.height - self.collectionView.contentInset.bottom - (self.collectionView.contentSize.height - self.collectionView.contentOffset.y))
let currentDistanceToBottomInset = max(0, self.collectionView.bounds.height - self.collectionView.contentInset.bottom - (contentSize.height - self.collectionView.contentOffset.y))
let newContentOffsetY = self.collectionView.contentOffset.y + insetBottomDiff - currentDistanceToBottomInset
self.collectionView.contentInset.bottom = newInsetBottom