I'm trying to add a shadow to my (custom) nav bar when a user scrolls using scrollViewDidScroll but it doesn't do anything. I have the same exact code on another view controller but it has a tableView instead of a WKWebView and it works fine.
I tried adding webView.scrollView.delegate = self but I just get an error.
My code:
class ViewController: UIViewController {
#IBOutlet weak var webView: WKWebView!
#IBOutlet weak var navBar: UIView!
override func viewDidLoad() {
super.viewDidLoad()
addShadow()
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let navigationBar = navBar
let offset = scrollView.contentOffset.y / 10
if offset > 1.5 {
navigationBar?.layer.shadowOpacity = 0.15
} else {
navigationBar?.layer.shadowOpacity = Float(((3 * offset) / 20)/1.5)
}
}
func addShadow() {
navBar.layer.shadowColor = UIColor.black.cgColor
navBar.layer.shadowOffset = CGSize(width: 0, height: 2.0)
navBar.layer.shadowRadius = 6.0
navBar.layer.masksToBounds = false
}
}
I tried adding webView.scrollView.delegate = self but I just get an error.
You didn't share what the error was. I suspect though that you didn't declare your view controller as UIScrollViewDelegate conforming, which caused the compile time error when trying to set self as the scroll view delegate.
Change your view controller declaration to this:
class ViewController: UIViewController, UIScrollViewDelegate {
Related
I followed this tutorial to create a Snapchat-Like Menu: https://www.youtube.com/watch?v=1_daE3IL_1s
In short, the idea was to create custom views with XIB, and add them into a scrollview.
I would like to add a "back" button to one of the custom views so that the scrollview will automatically scroll back to its initial view when the button is tapped. The Idea I had was to write a code inside the custom view's IBAction function to call UIScrollview's content offset delegate function.
the following is the code in View Controller:
class ViewController: UIViewController, UIScrollViewDelegate {
//I'm naming the Scroll View as "scrollView"
#IBOutlet weak var scrollView: UIScrollView! {
didSet{
scrollView.delegate = self
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
var v1 : View1 = View1(nibName: "View1", bundle: nil)
var v2 : View2 = View2(nibName: "View2", bundle: nil)
self.addChild(v1)
self.scrollView.addSubview(v1.view)
v1.didMove(toParent: self)
self.addChild(v2)
self.scrollView.addSubview(v2.view)
v1.didMove(toParent: self)
var v2Frame : CGRect = v2.view.frame
v2Frame.origin.x = self.view.frame.width
v2.view.frame = v2Frame
self.scrollView.contentSize = CGSize(width: self.view.frame.width * 2, height: self.view.frame.height)
// self.scrollView.contentSize = CGSize(self.view.frame.width * 2, self.view.frame.size.height)
}
}
The following ht the code in View2:
class View2: UIViewController {
#IBOutlet weak var buttonHome: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func buttonHomeAction(_ sender: Any) {
//how to access scrollview.setContentOffset from ViewController to scroll the view back to the first view?
}
So my question is how to access scrollview.setContentOffset from ViewController to scroll the view back to the first view? Am I on the right track? Or are there any alternative methods where I can tap a button and scroll the view back to its first page?
Thank you!
I can think of two good options here:
1) Hold a weak reference in View2 of the scrollView. in View2 add:
weak var scrollView: UIScrollView?
and in ViewController, after view2 creation add:
view2.scrollView = self.scrollView
now, in buttonHomeAction you'll have access to the scrollView.
2) If you are familiar with Apple's delegation pattern, you can add a delegate, which can be a weak reference of the presenting view controller.
Create a protocol for the delegate, using named by the view holds the delegate. so, in this case: View2Delegate
and add a method that describes the action.
protocol View2Delegate: AnyObject {
func buttonTapped()
}
so, in View2 add:
weak var delegate: View2Delegate?
and in ViewController, after view2 creation add:
view2.delegate = self
now, in ViewController implement the protocol method and access scrollView:
extension ViewController: View2Delegate {
func buttonTapped() {
// access scrollView as self.scrollView
}
}
I have a TextView and a hidden button within a UIView, and I'm trying to detect when the user scrolls down to the bottom of a long list of text and to show the hidden button when they reach the bottom. I saw some old posts on how it was done in Obj-C using scrollViewDidScroll, but not really sure how to do that with swift, or how to do it with a TextView instead of a ScrollView. Any help would be great as I haven't gone very far with this one.
So far this is my attempt at translating the obj-c post to swift, but it hasn't worked for me, in fact I'm not even sure when the function is called:
import UIKit
class MainVC: UIViewController, UIScrollViewDelegate {
#IBOutlet var textView: UIScrollView!
#IBOutlet var button: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
textView.delegate = self
}
func scrollViewDidScroll(textV: UIScrollView) {
if (textV.contentOffset.y >= textV.contentSize.height - textV.frame.size.height)
{
button.isHidden = false
}
}
}
Thanks for any help in advance :)
UITextView is subclass of UIScrollView and if you look to declaration, you will see, that it is UIScrollViewDelegate by default, so you can remove the UIScrollViewDelegate at the declaration of your controller. Instead, make your controller UITextViewDelegate which allows it to call scrollViewDidScrollMethod.
class ViewController: UIViewController, UITextViewDelegate {
#IBOutlet weak var textView: UITextView! {
didSet {
textView.delegate = self
}
}
#IBOutlet weak var button: UIButton! {
didSet {
button.hidden = true
}
}
func scrollViewDidScroll(scrollView: UIScrollView) {
button.hidden = scrollView.contentOffset.y + scrollView.bounds.height < scrollView.contentSize.height
}
}
(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
float bottomEdge = scrollView.contentOffset.y + scrollView.frame.size.height
if (bottomEdge >= scrollView.contentSize.height) {
self.yourButtonName.hidden = true
}
}
If the button is in the last of view(self.view) then I think you have to check that your contentOffset point is at the bottom of contentSize. So you could probably do something like:
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
float bottomEdge = scrollView.contentOffset.y +scrollView.frame.size.height;
if (bottomEdge >= scrollView.contentSize.height) {
self.yourButtonName.hidden = true
}
}
I created this UIImageView in Xcode and then added an image. See the picture below :
Then I added this code to try to change the UIImageView but its not working:
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var border: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
let width = UIScreen.mainScreen().bounds.width
let height = UIScreen.mainScreen().bounds.height
border.frame.size.width = width
border.frame.size.height = height
}
I believe you have to do this in ViewDidLayoutSubviews, not ViewDidLoad:
override func viewDidLayoutSubviews() {
}
I Have a scroll view that contains multiple view controllers. On those view controllers I have switches. When on switch is "on" all the other switches turn off. This is all done through the viewDidLoad.
I cannot get this to work though, I have tried putting the code for the switch thingy stuff that I am trying to do in viewWillAppear. It seems though that these two methods are only called at run time.
My alternative idea is to somehow "reset" the scroll view from inside one of the subviews
here is what i have:
class ViewController: UIViewController {
#IBOutlet weak var scrollView: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
let vc0 = ViewController0(nibName: "ViewController0", bundle: nil)
self.addChildViewController(vc0)
self.scrollView.addSubview(vc0.view)
vc0.didMoveToParentViewController(self)
let vc1 = ViewController1(nibName: "ViewController1", bundle:nil)
var frame1 = vc1.view.frame
frame1.origin.x = self.view.frame.size.width
vc1.view.frame = frame1
self.addChildViewController(vc1)
self.scrollView.addSubview(vc1.view)
vc1.didMoveToParentViewController(self)
let vc2 = ViewController2(nibName: "ViewController2", bundle:nil)
var frame2 = vc2.view.frame
frame2.origin.x = self.view.frame.size.width * 2
vc2.view.frame = frame2
self.addChildViewController(vc2)
self.scrollView.addSubview(vc2.view)
vc2.didMoveToParentViewController(self)
let vc3 = ViewController2(nibName: "ViewController3", bundle:nil)
var frame3 = vc3.view.frame
frame3.origin.x = self.view.frame.size.width * 3
vc3.view.frame = frame3
self.addChildViewController(vc3)
self.scrollView.addSubview(vc3.view)
vc3.didMoveToParentViewController(self)
self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width * 4, self.view.frame.size.height - 66);
}
}
^for the scrollUI creator class
import UIKit
class ViewController0: UIViewController {
#IBOutlet weak var onoff: UISwitch!
override func viewDidLoad() {
super.viewDidLoad()
onoff.on = false
}
#IBAction func used(sender: AnyObject) {
let parent = self.view.superview
parent?.setNeedsDisplay()
}
}
^this is one of the subclasses
This subclass has a switch and when toggled, it should "reset" the scroll view so all of the subviews viewDidLoad are called again...
This does not work.... Are there any solutions to this??
BTW sorry for the bad formatting for the code blocks.
I created a scroll view container that houses three view controllers. It's meant to mimic snapchat's swipe layout. however, I can't seem to get a code to manually switch to the next view controller without actually swiping (which I'm not interested in)
I tried calling the container class and setting it's scroll offset but it crashes... tried creating a delegate protocol, but delegate is returning nil... I'm stumped.
Here is my code:
class AViewController: UIViewController, ABViewControllerDelegate {
#IBOutlet var scrollView: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
// 1) Create the three views used in the swipe container view
var ATVc : ATViewController = ATViewController(nibName: "ATViewController", bundle: nil);
var ACVc : ACViewController = ACViewController(nibName: "ACViewController", bundle: nil);
var ABVc : ABViewController = ABViewController(nibName: "ABViewController", bundle: nil);
// 2) Add in each view to the container view hierarchy
// Add them in opposite order since the view hieracrhy is a stack
self.addChildViewController(ABVc);
self.scrollView!.addSubview(ABVc.view);
ABVc.didMoveToParentViewController(self);
self.addChildViewController(ACVc);
self.scrollView!.addSubview(ACVc.view);
ACVc.didMoveToParentViewController(self);
self.addChildViewController(ATVc);
self.scrollView!.addSubview(ATVc.view);
ATVc.didMoveToParentViewController(self)
// 3) Set up the frames of the view controllers to align
// with eachother inside the container view
var adminFrame :CGRect = ATVc.view.frame;
adminFrame.origin.y = adminFrame.height;
ACVc.view.frame = adminFrame;
var BFrame :CGRect = ACVc.view.frame;
BFrame.origin.y = 2*BFrame.height;
ABVc.view.frame = BFrame;
// 4) Finally set the size of the scroll view that contains the frames
var scrollWidth: CGFloat = self.view.frame.width
var scrollHeight: CGFloat = 3 * self.view.frame.size.height
self.scrollView!.contentSize = CGSizeMake(scrollWidth, scrollHeight)
self.scrollView!.setContentOffset(CGPointMake(0, self.view.frame.height), animated: false)
var changeMe : String = "okay"
}
func scrollUp() {
println("clicked!")
self.scrollView.contentOffset.y - self.view.frame.height
}
}
and this is the view controller I'm trying to get out off by pressing a button..
protocol ABViewControllerDelegate {
func scrollUp()
}
class ABViewController: UIViewController {
let delegate = ABViewControllerDelegate?()
#IBAction func button(sender: AnyObject) {
println("button clicked!")
delegate!.scrollUp()
}
}
I feel like I'm leading myself on and that it can't be done!