I have a label outside of a scrollview. I want to move the label from left to right of screen and vice versa when scrollview scrolling up and down.I wrote this code and it works when scrollview is scrolling in normal speed and when it scrolls very fast the label x position changes very slowly. How I can do that for all scrollview scrolling speeds?
func scrollViewDidScroll(_ scrollView: UIScrollView!) {
let offset = scrollView.contentOffset.y
let imahey = view.convert(placeImgview.frame, from:scrollview).origin.y + placeImgview.frame.width
print(offset)
let ratio: CGFloat = (-offset*1.0 / placeImgview.frame.height)
topBarView.alpha = -ratio
if placeName.frame.origin.x < -20 {
placeName.center = CGPoint(x: placeName.center.x - 3*ratio, y: placeName.center.y + ratio/1.5)
}
if (self.lastContentOffset > scrollView.contentOffset.y) {
placeName.center = CGPoint(x: placeName.center.x + 6*ratio, y: placeName.center.y - 2*ratio)
if offset == -20 {
placeName.frame.origin.x = -view.frame.width/2
placeName.frame.origin.y = 60
}
}
self.lastContentOffset = scrollView.contentOffset.y
}
So, the problem is that the faster you scroll, the larger the "gap" gets inbetween scrollViewDidScroll events.
You probably should consider to move around your label using UIView.animate... that would create a more consistent experience because the animation always has the same speed.
This way you could apply the animation using CGAffineTransform(translationX: , y: )
depending if your contentOffset.y passes a given threshold, whenever that label should appear or disappear.
Related
I am new to iOS.
I am having my collection view inside tableview cell.
There are 3 cells in collection view cell.
I need to show the second cell of collection view in center of the screen as shown in the image and also want to add pagination into it.
Any help will be appreciated.
Image
Thank You
I had to do a similar collection view a few months ago, This is the code that I use:
func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
let layout = theNameOfYourCollectionView.collectionViewLayout as! UICollectionViewFlowLayout
let cellWidthIncludingSpacing = layout.itemSize.width + layout.minimumLineSpacing // Calculate cell size
let offset = scrollView.contentOffset.x
let index = (offset + scrollView.contentInset.left) / cellWidthIncludingSpacing // Calculate the cell need to be center
if velocity.x > 0 { // Scroll to -->
targetContentOffset.pointee = CGPoint(x: ceil(index) * cellWidthIncludingSpacing - scrollView.contentInset.right, y: -scrollView.contentInset.top)
} else if velocity.x < 0 { // Scroll to <---
targetContentOffset.pointee = CGPoint(x: floor(index) * cellWidthIncludingSpacing - scrollView.contentInset.left, y: -scrollView.contentInset.top)
} else if velocity.x == 0 { // No dragging
targetContentOffset.pointee = CGPoint(x: round(index) * cellWidthIncludingSpacing - scrollView.contentInset.left, y: -scrollView.contentInset.top)
}
}
This code calculates the size of your cell, how many cells have already been shown and once the scroll is finished, adjust it to leave the cell centered.
Make sure you have the pagingEnabled of your collectionView in false if you want to use this code.
Also, implement UIScrollViewDelegatein your ViewController
I have a round Imageview in my ReusableCollectionView.
When I scroll down my collectionView I scale my Imageview and as soon as it scrolls back to place I scale it to its original size.
func scrollViewDidScroll(_ scrollView: UIScrollView) {
// Exit early if swiping up (scrolling down)
if scrollView.contentOffset.y > 0 { return }
// this is just a demo method on how to compute the scale factor based on the current contentOffset
var scale = 1.0 + fabs(scrollView.contentOffset.y) / scrollView.frame.size.height
//Cap the scaling between zero and 1
scale = max(0.0, scale)
// Set the scale to the imageView
headerView.imageview.transform = CGAffineTransform(scaleX: scale, y: scale)
headerView.categoryButton.transform = CGAffineTransform(scaleX: scale, y: scale)
}
The imageview is not round anymore while doing so.
Here is an image visualising the problem:
This is how I solved the problem:
imageView.autoresizesSubviews = false
I'm trying to zoom my image view as I scroll the scrollView past the top of the screen. Here's my code:
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let offset = scrollView.contentOffset.y
if (offset <= 0) {
let ratio: CGFloat = -offset*1.0 / UIScreen.main.bounds.height
self.coverImageView.transform = CGAffineTransform(scaleX: 1.0 + ratio, y: 1.0 + ratio)
}
}
This zooms the image as I scroll up, but because I am also scrolling up, my view goes down, and reveals the white background behind the image as it expands. How do I prevent that from happening?
It sounds like a scroll view is not really suited to what you are trying to do. How about using a gesture recognizer instead? Something along these lines:
override func viewDidLoad() {
super.viewDidLoad()
coverImageView.isUserInteractionEnabled = true
let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(didPan))
coverImageView.addGestureRecognizer(panGestureRecognizer)
}
func didPan(panGestureRecognizer: UIPanGestureRecognizer) {
let translation = panGestureRecognizer.translation(in: coverImageView)
if translation.y > 0 {
let zoomRatio = (translation.y * 0.1) + 1.0
coverImageView.transform = CGAffineTransform(scaleX: zoomRatio, y: zoomRatio)
}
}
You'll have to play around to get it to behave exactly how you want, but it should be enough to get you started.
In my Swift 2 iOS 9.0 project I've set up a UIScrollView with a UIImageView and some buttons and labels. For some other reasons the scrollView's frame is 652 points wide and 652 points high. Its content is decided by the image in the imageView (it's 1000x1000):
func loadImageOntoView(FloorImage:UIImage) -> Void {
mapImageView.image = FloorImage
// containerView is my root view, same size as the screen
let cw = containerView.frame.width
let ch = containerView.frame.height
let cd = sqrt(cw*cw + ch*ch)
/* Here I set scrollView's frame to be a square with sides as
long as containerView's diagonal. This makes sure that if the scrollView
is rotated it's always bigger than the screen*/
scrollView.frame = CGRect(
x: -(cd-cw)/2, y: -(cd-ch)/2,
width: cd, height: cd
)
scrollView.contentSize = FloorImage.size
//Here it centers the imageView in the scrollView
mapImageView.center = CGPoint(
x: scrollView.frame.size.width/2, y: scrollView.frame.size.height/2)
scrollView.minimumZoomScale = 0.9
scrollView.maximumZoomScale = 15.1
}
I'm not completely sure on these scrollViews, but I thought it was supposed to be able to scroll with these settings? When I zoom in I can scroll, but when the zoomScale = 1 it doesn't work. What have I done wrong, or how should I go about using scrollViews?
I have a scrollview with an UIImageView on it. When the user scrolls, I would like to keep the UIImageView at its original place. I am using offsetBy for this:
func scrollViewDidScroll(scrollView: UIScrollView) {
let offset = scrollView.contentOffset.y
self.headerView!.currentLoadLabel.frame = currentLoadLabelFrame.offsetBy(dx: 0, dy: offset)
}
The UIImageView stays at his y position but moves to the farmost x position at the right of the screen. Why?
try following code:
self.headerView!.currentLoadLabel.frame = currentLoadLabelFrame.offsetBy(dx: scrollView.contentOffset.x, dy: scrollView.contentOffset.y)