How to customize UIRefreshControl to make pull-down-height lower than default - ios

In UIRefreshControl in iOS App, I think the default setting is that when I pull down UITableView(UISrollView) by about "100px", refresh begins.
I would like to make the above value smaller.(for example, "50px")
Is this possible?
If possible, please tell me sample codes.

Try this:
// definition
extension UIRefreshControl {
func refreshManually() {
beginRefreshing()
sendActions(for: .valueChanged)
}
}
// usage
var isRefreshingManually = false
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView.contentOffset.y < -80.0 {
if !isRefreshingManually && !refreshControl.isRefreshing {
isRefreshingManually = true
refreshControl.refreshManually()
}
} else if scrollView.contentOffset.y >= 0 {
isRefreshingManually = false
}
}
My sample code is for UICollectionView, but UITableView & UIScollView work well, too.
Replace "-80.0" in my code to threshould value you want.

you can make it right with some modification
lazy var refreshControl: UIRefreshControl = {
let refreshControl = UIRefreshControl()
refreshControl.tintColor = UIColor.red
return refreshControl
}()
//refreshControl.addTarget(self, action: #selector(handleRefresh), for: .valueChanged)
every PullToRefresh must have couple lines of code like this, that handleRefresh function, do whatever you need to refresh the page.
you just need to comment out addTarget line and add this function to your code
```
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView.contentOffset.y < -80 { //change 80 to whatever you want
if !self.refreshControl.isRefreshing {
handleRefresh()
}
}
}

You can try this method. When UIRefreshControl is added before UITableView(UIScrollView) is appear , the height of the view may be bigger than the actually height the view display on screen , so the UIRefreshControl pull to refresh range is bigger than actual
let ori = tableView.frame
let temp_frame = CGRect.init(x: ori.origin.x, y: ori.origin.y, width:
ori.size.width, height: ori.size.height/1.3 )
tableView.frame = temp_frame
tableView.addSubview(UIRefreshControl())
tableView.frame = ori
This code modified the height of view before adding refreshControl , you can adjust the height based on your preference.

Related

Is it possible to add a drag to reload horizontally for a collection view?

Update:
I belive it may not be possible given the folowing line in apples documentation:
When the user drags the top of the scrollable content area downward
Found here.
Let me know if there is a way to do this.
I am trying to make it so that when the user swipe left (the way you swipe up in many apps with tableViews to reload) in a collection view it will show a loading icon and reload data (the reload data part I can handle myself).
How can I detect this so I can call a reloadData() method?
Note: I am using a UICollectionView which only has one column and x rows. At the first cell if the user swipes left it should show a loading icon and reload data.
I am looking for a way to detect the slide left intended to reload.
What I have tried:
let refreshControl = UIRefreshControl()
override func viewDidLoad() {
super.viewDidLoad()
viewDidLoadMethods()
refreshControl.tintColor = .black
refreshControl.addTarget(self, action: #selector(refresh), for: .valueChanged)
collectionView.addSubview(refreshControl)
collectionView.alwaysBounceHorizontal = true
But this only works vertically.
I solved this problem with the following, but I should note that there is no default fucntionality like there is for vertical refresh:
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let offset = scrollView.contentOffset
let inset = scrollView.contentInset
let y: CGFloat = offset.x - inset.left
let reload_distance: CGFloat = -80
if y < reload_distance{
shouldReload = true
}
}
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
if let _ = scrollView as? UICollectionView {
currentlyScrolling = false
if shouldReload {
baseVC.showReloading()
reloadCollectionView()
}
}
}

Detect when y offset changes in scrollView with paging enabled

I would like to find out which page is visible to the user and also do a certain action when a change in the page is detected. To do this I am using the function scrollViewDidScroll. As I didn't get the result I wanted (nothing happened), I looked for answers on stackoverflow and found the following question which was answered: Detecting UIScrollView page change, to be more precise I used the answer by Michael Waterfall and converted the Objective-C code to swift code.
Below you will find the code I used to create the scrollView in my class HomeController: UIViewController, UIScrollViewDelegate {. Moreover the function by Michael Waterfall is declared and called in the function initiateScrollView(). However, the function doesn't print anything. Do you know where I am doing something wrong? I can't see where I made a mistake. Nothing happens when I scroll (e.g. from page 1 to page 2 (homeView to view2)). The function only prints before: 0 once and after that nothing happens.
Code
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
initiateScrollView()
}
func initiateScrollView() {
//create scrollView with paging enabled
let scrollView = UIScrollView(frame: view.bounds)
scrollView.isPagingEnabled = true
view.addSubview(scrollView)
//get page size
let pageSize = view.bounds.size
//individual views
let homeView = UIView()
homeView.backgroundColor = .green
let view2 = UIView()
view2.backgroundColor = .blue
let view3 = UIView()
view3.backgroundColor = .red
//array with individual views
let pagesViews = [homeView, view2, view3]
//amount of views
let numberOfPages = pagesViews.count
print(numberOfPages) //prints '3'
//add subviews (pages)
for (pageIndex, page) in pagesViews.enumerated(){
//add individual pages to scrollView
page.frame = CGRect(origin: CGPoint(x:0 , y: CGFloat(pageIndex) * pageSize.height), size: pageSize)
scrollView.addSubview(page)
}
func scrollViewDidScroll(scrollView: UIScrollView) {
var previousPage = 0
let fractionalPage: Float = Float(scrollView.contentOffset.y / pageSize.height)
let page = lround(Double(fractionalPage))
print("before:", page) //prints 'before: 0' once
if previousPage != page {
// Page has changed, do your thing!
// ...
// Finally, update previous page
print("before:", page)
previousPage = page
print("after:", page)
} //never prints anything
}
scrollViewDidScroll(scrollView: scrollView)
//define size of scrollView
scrollView.contentSize = CGSize(width: pageSize.width, height: pageSize.height * CGFloat(numberOfPages))
}
You forgot to set the viewController as the delegate for the scroll view, as following:
func initiateScrollView() {
//create scrollView with paging enabled
let scrollView = UIScrollView(frame: view.bounds)
scrollView.isPagingEnabled = true
scrollView.delegate = self
view.addSubview(scrollView)
(...) }
And I recommend that you use the scrollViewDidEndScrollingAnimation(_ scrollView: UIScrollView) function, instead of scrollViewDidScroll(...)
This is because you haven't set the delegate property of your scrollview.
Add scrollView.delegate = self in your initiateScrollView method.

Nested UICollectionView does not hide NavigationBar on swipe

I have a UICollectionViewController (embedded in a NavigationViewController), which scrolls a UICollectionView horizontally via paging through some sections:
if let flowLayout = collectionView?.collectionViewLayout as? UICollectionViewFlowLayout {
flowLayout.scrollDirection = .horizontal
flowLayout.minimumLineSpacing = 0
}
collectionView?.backgroundColor = .white
collectionView?.register(FeedCell.self, forCellWithReuseIdentifier: cellId)
//collectionView?.contentInset = UIEdgeInsetsMake(MenuBar.height, 0, 0, 0)
//collectionView?.scrollIndicatorInsets = UIEdgeInsetsMake(MenuBar.height, 0, 0, 0)
collectionView?.isPagingEnabled = true
Each section or page contains another UICollectionView (inside the FeedCell) which scrolls vertically through some UICollectionViewCells.
Inside the UICollectionViewController, I set
navigationController?.hidesBarsOnSwipe = true
which was working as long as there was only one UICollectionView. But since the (Top)CollectionView is scrolling horizontally and is containing additional (Sub)CollectionView, that are scrolling vertically, this feature seems not to work any longer.
I would like the NavigationBar to hide when the (Sub)CollectionView is scrolling vertically. Is there any hack to achieve this?
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if let navigationBar = self.navigationController?.navigationBar {
let clampedYOffset = contentOffset.y <= 0 ? 0 : -contentOffset.y
navigationBar.transform = CGAffineTransform(translationX: 0, y: clampedYOffset)
self.additionalSafeAreaInsets.top = clampedYOffset
}
}
This is a solution that I came up with. Basically modify the transform of the NavigationBar to move it out the way when necessary. I also modify the additionalSafeAreaInset, as this will automatically shift all your content up to fill the space left by the navigation bar.
This function will be called as part of the UICollectionViewDelegate protocol.
This was suitable for my purposes - but if you want the navigation bar to appear when the user rapidly scrolls up (like in safari) you will have to add some additional logic.
Hope this helps!
You can try the code like this (Swift 3.0):
extension ViewController: UICollectionViewDelegate {
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let isScrollingUp = scrollView.contentOffset.y - lastY > 0
lastY = scrollView.contentOffset.y
self.navigationController?.setNavigationBarHidden(isScrollingUp, animated: true)
}
func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
if !decelerate {
// show navigation bar ?
}
}
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
// show navigationBar ?
}
}

Animate headerView of TableView while pulling down UITableView in swift

I am trying to create a growing UITableViewHeader on UITableView. I have a UITableView and a mapView set in the tableHeaderView of UITableView.
tblView.bounces = true
tblView.bouncesZoom = true
tblView.alwaysBounceVertical = true
mapView.frame = CGRectMake(0, 0, self.view.frame.size.width, CGFloat(kMapHeaderHeight))
mapView.mapType = MKMapType.Standard
mapView.zoomEnabled=true
mapView.scrollEnabled = true
mapView.delegate = mapHelper
tblView.tableHeaderView = mapView
And also implemented scrollViewDidScroll delegate and whenever it scrolls down, I have changed the frame of headerview as
func scrollViewDidScroll(scrollView: UIScrollView) {
var scrollOffset = scrollView.contentOffset.y
println("\(scrollOffset)")
var headerFrame : CGRect = self.mapView.frame
if (scrollOffset < 0){
headerFrame.size.height -= scrollView.contentOffset.y/3
}
self.mapView.frame = headerFrame
}
However, it does not grow as expected without bouncing.Seems very unclear. Any help?
I am following these tutorials to create a Growing UITableViewheader when pulling down as
UITableVIew header without bouncing when pull down ,
Expand UITableView Header View to Bounce Area When Pulling Down
Here is the link of the project :
https://drive.google.com/file/d/0B6dTvD1JbkgBVENUS1ROMzI0Wnc/vie
EDITED: i somehow managed to have the effect but the animation seems very slow
func scrollViewDidScroll(scrollView: UIScrollView) {
let yPos: CGFloat = -scrollView.contentOffset.y
if (yPos > 0) {
var mapViewRect: CGRect = self.mapView.frame
mapViewRect.origin.y = scrollView.contentOffset.y
mapViewRect.size.height = kHeaderHeight+yPos
self.mapView.frame = mapViewRect
}
}
let kHeaderHeight:CGFloat = 200
I suggest you to use this tutorial.
The most important parts of it:
Create a scrollView (or whatever that is a subclass of a UIScrollView) and a separate view (which will be functioning as a headerView, so let's call if headerView)
add the headerView and the scrollView as a subView of your view
implement the scrollViewDidScroll method, and put the framing logic there (of course, if you're using autolayout, you have to manage constraints there)
Actually the animation was not working well in simulator of xcode6.3. I tried 2 days for this and posted a bounty here but when i finally I tested it on real device and found the MapView was properly bouncing.If anyone needs it..here is the piece of logic.
let kHeaderHeight:CGFloat = 380
class NewBookingVC: UIViewController {
#IBOutlet weak var tblView: UITableView!
let mapView : MKMapView = MKMapView()
var customTableHeaderView:UIView = UIView()
override func viewDidLoad() {
super.viewDidLoad()
tblView.delegate = self
tblView.dataSource = self
mapView.frame = CGRectMake(0, 0, self.view.frame.size.width, 380)
mapView.mapType = MKMapType.Standard
mapView.zoomEnabled=true
mapView.scrollEnabled = true
customTableHeaderView = UIView(frame: CGRectMake(0, 0, self.view.frame.size.width, 380))
customTableHeaderView.addSubview(mapView)
tblView.tableHeaderView = customTableHeaderView
}
func scrollViewDidScroll(scrollView: UIScrollView) {
let yPos: CGFloat = -scrollView.contentOffset.y
if (yPos > 0) {
var mapViewRect: CGRect = self.mapView.frame
mapViewRect.origin.y = scrollView.contentOffset.y
mapViewRect.size.height = kHeaderHeight+yPos
self.mapView.frame = mapViewRect
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
Actually what you have to do is implement the scrollview delegate for table view because it inherits from scrollview and you can implement scrollViewDidScroll delegate and whenever it scrolls down, change the frame of headerview.
Idea behind this while scrolling you always have to keep the y-position of the MKMapView at the zero position....and height should incerase accordingly...
func scrollViewDidScroll(scrollView: UIScrollView) {
let yPos: CGFloat = -scrollView.contentOffset.y
if (yPos > 0) {
//adjust your mapview y-pos and height
//adjusting new position is all about real math
}
}
Performance in the iOS Simulator is not expected to match performance on device. The iOS Simulator is meant as a tool for rapid prototyping and fast iteration.In your case too, redrawing of MapView performance is quite slow in the simulator because at each Scroll you are calculating its new frame and height. So it takes some time adjusting new frame and seems very slow.
However it works well while tuning on real devices.

How is the pull distance calculated for a UIRefreshControl

Just to be clear, I don't want to change the distance, I just want to know what it is as I'm doing some other UI stuff at the same time. Is it a fixed distance or a function of the height of the associated UITableView?
The pull distance seems to be very close to 50% of the tableView height.
FYI: You can't modify the pull distance of UIRefreshControl.
Check my other answer for an alternative.
if you want to change the distance you use a little trick.
you can make it right with some modification
lazy var refreshControl: UIRefreshControl = {
let refreshControl = UIRefreshControl()
refreshControl.tintColor = UIColor.red
return refreshControl
}()
//refreshControl.addTarget(self, action: #selector(handleRefresh), for: .valueChanged)
every PullToRefresh must have couple lines of code like this, that handleRefresh function, do whatever you need to refresh the page.
you just need to comment out addTarget line and add this function to your code
```
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView.contentOffset.y < -80 { //change 80 to whatever you want
if !self.refreshControl.isRefreshing {
handleRefresh()
}
}
}
I wrote this code with the help of Ashkan Ghodrat's answer

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