I don't know if this is possible and I highly doubt that it is but I'm wondering if there's a way where I can prevent a button for example from scrolling in a UIScrollView using Objective-C programming?
Sure. Simply update the button's origin as the scroll view scrolls.
In your view controller, implement the appropriate scroll view delegate method. If not done already, setup your view controller as the scroll view's delegate.
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
CGPoint offset = scrollView.contentOffset;
CGRect frame = self.fixedButton.frame;
frame.origin.y = offset.y + 40;
self.fixedButton.frame = frame;
}
This will keep the self.fixedButton button 40 points below the top of the visible portion of the scroll view. Adjust as needed.
The above all assumes the button is a subview of the scroll view.
Of course it may be a lot easier if the button and the scroll view share a common parent view. Then the button isn't a subview of the scroll view and won't scroll at all.
I'm trying to figure out the best way to have a custom inputAccessoryView rest on top of a tab bar. Currently, I have an inputAccessoryView that rests at the very bottom of the screen, but it covers the tab bar. Any one know the best practice for shifting that inputAccessoryView up?
Currently I have a view defined in a storyboard with a tab bar. Its corresponding view controller takes the view and calls becomeFirstResponder. I've overwritten both:
- (UIView *)inputAccessoryView and -(BOOL)canBecomeFirstResponder
within the view's .m
Found a workaround by shifting toolbar frame by bottomSpacing = tabbar height:
- (void) layoutSubviews {
[super layoutSubviews];
CGRect origFrame = self.frame;
origFrame.origin.y = _keyboardIsVisible ? 0 : -self.bottomSpacing;
self.frame = origFrame;
}
Strangely it works well in JSQMessagesInputToolbar, but it's lost after animations if I do this in UIView that wraps toolbar, or maybe I'm missing something..
I have a view controller that on certain action presents another view controller that covers bottom half of the screen.
When I animate the second view controller (presented view controller) from the bottom to cover the bottom half of the screen, I also want animate the presenting view to top half of the screen. See the code below -
- (void)animatePresentationWithTransitioningContext:(id<UIViewControllerContextTransitioning>) transitioningContext
{
UIViewController *presentedController = [transitioningContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *presentedControllerView = [transitioningContext viewForKey:UITransitionContextToViewKey];
UIView *containerView = [transitioningContext containerView];
presentedControllerView.frame = [transitioningContext finalFrameForViewController:presentedController];
CGPoint center = presentedControllerView.center;
center.y = containerView.bounds.size.height;
presentedControllerView.center = center;
[containerView addSubview:presentedControllerView];
// This returns nil
UIView *presentingControllerView = [transitioningContext viewForKey:UITransitionContextFromViewKey];
[UIView animateWithDuration:[self transitionDuration:transitioningContext] delay:0.0 usingSpringWithDamping:1.0 initialSpringVelocity:0.0 options:UIViewAnimationOptionAllowUserInteraction animations:^{
CGPoint presentedViewCenter = presentedControllerView.center;
presentedViewCenter.y -= containerView.bounds.size.height/2.0;
presentedControllerView.center = presentedViewCenter;
// This is where I want to move the presenting view controller.
// of course it does not work.
CGPoint presentingViewCenter = presentingControllerView.center;
presentingViewCenter.y -= containerView.bounds.size.height/2.0;
presentingControllerView.center = presentingViewCenter;
} completion:^(BOOL finished) {
[transitioningContext completeTransition:finished];
}];
}
The viewForKey:UITransitionContextFromViewKey returns nil. I overrode shouldRemovePresentersView to return NO in my custom UIPresentationController but I still get nil. I am using UIModalPresentationCustom as the modal presentation style for the view that I am presenting.
EDIT:
I realized that I can achieve the same affect by animating the presenting view by overriding the presentationTransitionWillBegin method in my custom UIPresentationController. But I would like to get an answer on accessing the presenting view controller.
EDIT:
Since I have found a solution, clarifying my question: (1) Is this the expected behavior i.e. the presentingViewController is going to be nil in the animator object?
I am using UIModalPresentationCustom as the modal presentation style for the view that I am presenting.
Well, there's your problem. In that case, the From view will be nil. It is nil unless you are using the FullScreen presentation style.
I'm not saying you are wrong to make the presentation style Custom. You need to do that, if you want to leave the presenting view controller's view in place, and if you want to supply your own presentation controller. And you do! But in that case, the work is divided: it is the presentation controller that becomes responsible for the final position of the view.
By the way, it occurs to me (thinking about it some more) that you are doing something you should probably not be doing. You are not expected to move the presenting view controller's view. It might be safer to take a snapshot view of the presenting view controller's view and animate that, behind your presented view controller's view.
I have the following layout (see below), which for most circumstances works just fine. The user is able to scroll within the blue UIScrollView (which for all intents and purposes is a UITableView, but this question generalises this), and then when they've reached the end of this scroll view, they can start scrolling again (they have to take their finger off, and on again, because the inner scroll view rubberbands otherwise), and the 'super' scroll view starts scrolling, revealing the rest of the image.
It's the whole (they have to take their finger off, and on again, because the inner scroll view rubberbands otherwise) that I don't want. Ideally, once the contained UIScrollView reaches the end of its content, I want the superview to take over scrolling straight away, so that the inner scroll view doesn't rubberband.
The same goes when the user is scrolling back up; when the red scrollview reaches the top of it's content, I want the inner blue scroll view to start scrolling up straight away, instead of the red scroll view rubberbanding at the top.
Any idea how? I am able to determine when the scroll views have reached the ends of their content, but I'm not sure how to apply this knowledge to achieve the effect I'm after. Thanks.
// Inner (blue) scroll view bounds checking
if (scrollView.contentOffset.y + scrollView.frame.size.height > scrollView.contentSize.height) { ... }
// Outer (red) scroll view bounds checking
if (scrollView.contentOffset.y < 0) { ... }
Yeah. Ive got a nifty trick for you.
Instead of having your red outlined view a scrollview make it a normal UIView that fills the screen. In that view lay out your scroll view (table view) and image view as they are in your illustration.
Place a scrollview that fills the bounds of the root view (i.e. also fills the screen) above all the other scrollview and image views. Set the content size of this view to be the total content height of all the views you want to scroll through. In otherwords there is an invisible scrollview sitting on top of all your other views and its content size height is inner scrollview (tableview) content size height + image view size height.
The heierarchy should look like this:
Then this scrollview on top that you have made with the really tall content size make its delegate be your view controller. Implement scrollViewDidScroll and we'll work some magic.
Scrollviews basically scroll by adjusting the bounds origin with funky formulas for momentum and stuff. So in our scrollviewDidScroll method we will simply adjust the bounds of the underlying views:
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
//the scroll view underneath (in the container view) will have a max content offset equal to the content height
//but minus the bounds height
CGFloat maxYOffsetForUnderScrollView = self.underScrollView.contentSize.height - self.underScrollView.bounds.size.height;
CGRect scrolledBoundsForContainerView = self.view.bounds;
if (scrollView.contentOffset.y <= maxYOffsetForUnderScrollView) {
//in this scenario we are still within the content for the underScrollView
//so we make sure the container view is scrolled to the top and set the offset for the contained scrollview
self.containerView.bounds = scrolledBoundsForContainerView;
self.underScrollview.contentOffset = scrollView.contentOffset;
return;
}
//in this scenario we have scrolled throug the entirety of the contained scrollview
//set its offset to the max and change the bounds of the container view to scroll everything else.
self.underScrollView.contentOffset = CGPointMake(0, maxYOffsetForUnderScrollView);
scrolledBoundsForContainerView.origin.y = scrollView.contentOffset.y - maxYOffsetForUnderScrollView;
self.containerView.bounds = scrolledBoundsForContainerView;
}
You will find that as scrollViewDidScroll is called every frame of animation that this faux scrolling of the contained views looks really natural.
But wait! I hear you say. That scroll view on top now intercepts ALL touches, and the views underneath it need to be touched as well. I have an interesting solution for that as well.
Set the scrollview on top to be off screen somewhere (i.e. set its frame off screen, but still the same size.) and then in your viewDidLoad method you add the scrollview's panGestureRecogniser to the main view. This will mean that you get all the iOS natural scrolling momentum and stuff without actually having the view on the screen. The contained scroll view will now probably go juddery as its pan gesture recognizer will get called as well (they work differently to UIEvent handling) so you will need to remove it.
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self.view addGestureRecognizer:self.scrollview.panGestureRecognizer];
[self.underScrollview removeGestureRecognizer:self.underScrollView.panGestureRecognizer];
//further code to set up content sizes and stuff
}
I had fun making this so heres a link to the sample project on github:
https://github.com/joelparsons/multipleScrollers
EDIT:
To show the scrollbar for the top scrollview when its off the screen no matter where you put it you can set the scrollIndicatorInsets to an inset created like this:
CGPoint scrollviewOrigin = self.scrollview.frame.origin;
self.scrollview.scrollIndicatorInsets = UIEdgeInsetsMake(-scrollviewOrigin.y,0,scrollviewOrigin.y,scrollviewOrigin.x);
*caveat that the scrollview still has to be the right height but I'm sure you get the idea.
And then to make the bar draw outside the scrollview's visible bounds you have to turn off clips to bounds
self.scrollview.clipsToBounds = NO;
OMG. jackslash, you saved my life.
In my case, I need to use three depth of scroll views.
Parent Scroll View
that has a scroll view as one of the children
Child Scroll View: shown as 'Explanation Scroll View / Review Table View / Information Scroll View' in the below image)
Hidden Scroll View
which is distribute own content offset to 'Parent Scroll View' and 'Child Scroll View'
which has content size of whole flatten contents
Screenshot of view hierarchy
After setting view hierarchy, I just need to sync whole flatten content size and distribute content offset properly.
Observable.combineLatest(
overviewStackView.rx.observe(CGRect.self, #keyPath(UIStackView.frame)).unwrap(),
explanationScrollView.rx.observe(CGSize.self, #keyPath(UIScrollView.contentSize)).unwrap()
)
.subscribe(onNext: { [weak self] overviewStackViewFrame, explanationScrollViewContentSize in
guard let self = self else { return }
let totalContentHeight = overviewStackViewFrame.height + self.segmentedControl.frame.height + explanationScrollViewContentSize.height
self.hiddenScrollView.contentSize.height = totalContentHeight
})
.disposed(by: disposeBag)
hiddenScrollView.rx.didScroll
.subscribe(onNext: { [weak self] _ in
guard let self = self else { return }
let currentHiddenScrollViewOffsetY = self.hiddenScrollView.contentOffset.y
let parentScrollViewMaxOffsetY = self.overviewStackView.frame.height
let expectedChildScrollViewOffsetY = max(currentHiddenScrollViewOffsetY - parentScrollViewMaxOffsetY, 0)
self.parentScrollView.contentOffset.y = min(parentScrollViewMaxOffsetY, currentHiddenScrollViewOffsetY)
self.explanationScrollView.contentOffset.y = expectedChildScrollViewOffsetY
})
.disposed(by: disposeBag)
I put a UIScrollView in my nib's view, and linked it to a an IBOutlet property.
Now, when I do this in my viewDidLoad method, it seems to have no effect on the contentSize:
self.sv.backgroundColor = [UIColor yellowColor]; // this works
CGSize size = CGSizeMake(1000.0, 1000.0);
[self.sv setContentSize:size]; // this does not
It behaves as if the contentSize was the same as the frame. What's going on?
This started working when I turned off AutoLayout. Why?
I had the same problem. Auto Layout for UIScrollView is messed up.
Work around: Put everything in the UIScrollView into another UIView, and put that UIView as the only child of the UIScrollView. Then you can use Auto Layout.
If things near the end is messed up (the end of whichever direction your UIScrollView scrolls), change the constraint at the end to have the lowest possible priority.
I tried viewWillLayoutSubviews to update scrollView's contentSize, it worked for me.
- (void)viewDidLayoutSubviews
{
[self.bgScrollView setContentSize:CGSizeMake(320, self.view.frame.size.height* 1.5)];
}
Apple Doc
-(void)viewDidLayoutSubviews
Called to notify the view controller that its view has just laid out its subviews.
Discussion
When the bounds change for a view controller’s view, the view adjusts the positions of its subviews and then the system calls this method. However, this method being called does not indicate that the individual layouts of the view’s subviews have been adjusted. Each subview is responsible for adjusting its own layout.
Your view controller can override this method to make changes after the view lays out its subviews. The default implementation of this method does nothing.
The easiest/cleanest way is to set contentSize at viewDidAppear so you negate the effects of autolayout. This doesn't involve adding random views. However relying on load order for an implementation to work may not be the best idea.
Use this code. ScrollView setContentSize should be called async in main thread.
Swift:
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
DispatchQueue.main.async {
var contentRect = CGRect.zero
for view in self.scrollView.subviews {
contentRect = contentRect.union(view.frame)
}
self.scrollView.contentSize = contentRect.size
}
}
Objective C:
- (void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
dispatch_async(dispatch_get_main_queue(), ^ {
CGRect contentRect = CGRectZero;
for(UIView *view in scrollView.subviews)
contentRect = CGRectUnion(contentRect,view.frame);
scrollView.contentSize = contentRect.size;
});
}
There are two problems here. (1) viewDidLoad is too soon; you have to wait until after layout has taken place. (2) If you want to use autolayout with a scrollview that comes from a nib, then either you must use constraints to completely describe the size of the contentSize (and then you don't set the contentSize in code at all), or, if you want to set it in code, you must prevent the constraints on the scrollview's subviews from dictating the contentSize. It sounds like you would like to do the latter. To do so, you need a UIView that acts as the sole top-level subview of the scrollview, and in code you must set it to not use autolayout, enabling its autoresizingMask and removing its other external constraints. I show an example of how to do that, here:
https://github.com/mattneub/Programming-iOS-Book-Examples/blob/master/ch20p573scrollViewAutoLayout/ch20p573scrollViewAutoLayout/ViewController.m
But notice also the next example, which shows how to use constraints completely, instead of contentSize.
A SUPER easy way to use AutoLayout with UIScrollViews inside Interface Builder:
Step 1: Create a UIScrollView
Step 2: Create a UIView that is a child of your scroll view like so:
-UIScrollView
---UIView
-----Your other content
(We'll call this one contentView).
Step 3: In the size inspector, give this view a height and width (say, 320x700).
Step 4 (using AutoLayout): Create unambiguous constraints from your contentView to its superview (the UIScrollView): connect the 4 edges (top, leading, trailing, bottom), then give it a defined width and height that you want it to scroll too.
For example: If your scroll view spans the entire screen, you could give your content view a width of [device width] and a height of 600; it will then set the content size of the UIScrollView to match.
OR:
Step 4 (not using AutoLayout): Connect both of these new controls to your view controller using IB (ctrl+drag from each control to your view controller's .h #implementation). Let's assume each is called scrollView and contentView, respectively. It should look like this:
#interface YourViewController : UIViewController
#property (strong, nonatomic) IBOutlet UIScrollView *scrollView;
#property (strong, nonatomic) IBOutlet UIView *contentView;
#end
Step 5 (not using AutoLayout): In the view controller's .h file add (actually, override) the following method:
-(void)viewDidLayoutSubviews
{
[super viewDidLayoutSubviews];
self.scrollView.contentSize = self.contentView.frame.size;
}
You can use this lines of code into your *.m file's
- (void)viewDidLoad{
[scroll setContentSize:CGSizeMake(320, 800)] ;
[scroll setScrollEnabled:TRUE];
[scroll setShowsVerticalScrollIndicator:NO];
[scroll setShowsHorizontalScrollIndicator:YES];
}
for this you need to take an IBOutlet property of UIScrollView into your *.h file this way:
IBOutlet UIScrollView *scroll;
And connect this from Storyboard.
Or,
You can use this method into your *.m file:
-(void)viewDidLayoutSubviews
{
[scroll setContentSize:CGSizeMake(320, self.view.frame.size.height* 1.5)];
// this will pick height automatically from device's height and multiply it with 1.5
}
This both solution works for me in xcode-5, xcode-6, xcode-6.1, xcode-6.2
Setting the contentSize in viewDidAppear is critical.
But I also had a variation of what worked in the 3.5 inch screen, and the 4 inch screen. The 4 inch screen worked, the older one does not. Both iOS 7. Bizarre is an understatement!
I could never get auto layout based on constraints to work. Since my view was already a subclass UIScrollView I solved it by overriding setContentView: and ignoring auto layouts zero height setContentSize: message.
#interface MyView : UIScrollView {}
#end
#implementation MyView
- (void)setContentSize:(CGSize)aSize {
if (aSize.height > 0)
[super setContentSize:aSize];
}
#end
I used to do set up the uiscrollview programmatically UNTIL I watched the following wonderful tutorial, step by step how to get uiscrollview and uiview to work: https://www.youtube.com/watch?v=PgeNPRBrB18
After watching the video you will start liking Interface Builder I am sure.
Vote up
Still not scrolling when dynamic height of labels exceeds view height.
I did what yuf's answer marked as correct above said to do (I added a content view to my scrollview and set the constraints leading, trailing, top bottom, and equal widths from the content view to the scroll view.) but still my view was not scrolling when the internal controls height exceeded the height of the scrollview.
Inside my content view I have an image and 3 labels below it. Each label adjusts their own height dependant on how much text is in them (they are set to word-wrap and numberoflines = 0 to achieve this).
The problem I had was my content view's height was not adjusting with the dynamic height of the labels when they exceeded the height of the scroll view/main view.
To fix this I worded out I needed to set the Bottom Space to Container constraint between my bottom label and the contentview and gave it a value of 40 (chosen arbitrarily to give it a nice margin at the bottom). This now means that my contentview adjusts its height so that there is a space between the bottom of the last label and itself and it scrolls perfectly!
Yay!
Try this out...
add all constraints like you do for UIView (See screenShot of my ViewControler in Storyboard)
Now trick begins. select your last object and select its bottom constraint. (See above screenShot, Instagram button's Bottom Constraint(Yellow line)) and Change the Constant in Size Inspector like in bellow screenshot.
i require Constant=8 but you can change as per your requirements.
this Constant is the Space between That Orange Button's Bottom and the scrollView.
EDIT
Make Sure about your view's hierarchy .
0) ViewController.view (optional)
1) UIScrollView
2) UIView (Rename as "contentView")
3) UIView (this view is your content that will make scrollView scroll)
I finally worked out my own solution to this problem because in my case I couldn't use the view controller's life cycle. Create your own scroll view subclass and use it instead of UIScrollView. This even worked for a scroll view inside a collection view cell.
class MyScrollView:UIScrollView {
var myContentSize:CGSize = CGSize.zero // you must set this yourself
override func layoutSubviews() {
super.layoutSubviews()
contentSize = myContentSize
}
}
My MyScrollView was defined in the nib with a tag of 90. If so this is a good way to set content size in the code in the parent view.
let scrollView = viewWithTag(90) as! MyScrollView
scrollView.myContentSize = ...
If you are using AutoLayout a really easy way to set the contentSize of a UIScrollView is just to add something like this:
CGFloat contentWidth = YOUR_CONTENT_WIDTH;
NSLayoutConstraint *constraintWidth =
[NSLayoutConstraint constraintWithItem:self.scrollView
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:self.scrollView
attribute:NSLayoutAttributeLeading
multiplier:1
constant:contentWidth];
[self.scrollView addConstraint:constraintWidth];
I got Autolayout to work for paginated scroll views whose pages occupy the full-width of the screen. The pages automatically resize according to the scroll view's size. I haven't tested this for lesser-width scroll views but do comment away if it works--I beleieve it should. Targeted for iOS 9, wrote code in Swift 2, used a mix of IB's and custom code in awakeFromNib.
Steps:
Define a full-screen scroll view.
Inside the scroll view, add a UIView (I called mine contentView) whose top, trailing, bottom, and leading edges to the scroll view are all zero; the height is equal to the scroll view's; but the width is the scroll view's width times the number of pages. If you're doing this visually, you will see your content view extend beyond your scroll view in Inteface Builder.
For every "page" inside the contentView, add Autolayout rules to put them side-by-side each other, but most importantly, give them each a constraint so that their widths are equal to the scroll view's, not the content view's.
Sample code below. embedChildViewController is just my convenience method for adding child VCs--do look at setupLayoutRulesForPages. I have exactly two pages so the function is too simple, but you can expand it to your needs.
In my view controller:
override func loadView() {
self.view = self.customView
}
override func viewDidLoad() {
super.viewDidLoad()
self.embedChildViewController(self.addExpenseVC, toView: self.customView.contentView, fillSuperview: false)
self.embedChildViewController(self.addCategoryVC, toView: self.customView.contentView, fillSuperview: false)
self.customView.setupLayoutRulesForPages(self.addExpenseVC.view, secondPage: self.addCategoryVC.view)
}
My custom view:
class __AMVCView: UIView {
#IBOutlet weak var scrollView: UIScrollView!
#IBOutlet weak var contentView: UIView!
#IBOutlet weak var pageControl: UIPageControl!
override func awakeFromNib() {
super.awakeFromNib()
self.scrollView.pagingEnabled = true
self.scrollView.bounces = true
self.scrollView.showsHorizontalScrollIndicator = false
self.scrollView.showsVerticalScrollIndicator = false
self.pageControl.numberOfPages = 2
self.contentView.backgroundColor = UIColor.blueColor()
self.scrollView.backgroundColor = UIColor.clearColor()
self.backgroundColor = UIColor.blackColor()
}
func setupLayoutRulesForPages(firstPage: UIView, secondPage: UIView) {
guard self.contentView.subviews.contains(firstPage) && self.contentView.subviews.contains(secondPage)
else {
return
}
let rules = [
"H:|-0-[firstPage]-0-[secondPage]-0-|",
"V:|-0-[firstPage]-0-|",
"V:|-0-[secondPage]-0-|"
]
let views = [
"firstPage" : firstPage,
"secondPage" : secondPage
]
let constraints = NSLayoutConstraint.constraintsWithVisualFormatArray(rules, metrics: nil, views: views)
UIView.disableAutoresizingMasksInViews(firstPage, secondPage)
self.addConstraints(constraints)
// Add the width Autolayout rules to the pages.
let widthConstraint = NSLayoutConstraint(item: firstPage, attribute: .Width, relatedBy: .Equal, toItem: self.scrollView, attribute: .Width, multiplier: 1, constant: 0)
self.addConstraint(widthConstraint)
}
}