As you can see in the attached image if I keep scrolling past the last object in my scrollview I can keep scrolling and then see the background. Is there a way to limit this in xcode so you can't scroll past the last object in the scroll view?
I'm new to xcode and did try researching this issue though I believe my terminology is impacting this.
Thanks
you will need to set the scrollView.contentSize size so that it fits around all your objects in the scroll view. if you have a way to determine which object is the lowest then you can use its origin + height to determine the height of the content size.
float maxHeight = 0;
for(UIView *v in [scrollView subviews]){
if(v.frame.origin.x + v.frame.size.height > maxHeight)
maxHeight = v.frame.origin.x + v.frame.size.height;
}
self.scrollView.contentSize = CGSizeMake(scrollView.frame.size.width, maxHeight+5);
Related
I've done quite a bit of looking into this but have been unsuccessful in finding a solution.
I have a UIScrollView called scrollView inside of UIView. I'm using this scrollView in pagingEnabled mode. Inside of scrollView, I have 3 different views created programmatically. Inside of these 3 different views, I have a bunch of stuff(UILabel,UITextView etc.). All of the views contents are dynamic and determined at runtime.So, i really don't know scrollView.contentSize. If i give the content size of this scrollView,Sometimes ,I have a screen with white blank at the botton of the screen when user scrolls down. My question is : Can i set the content size dynamically for each single page of this scrollView? For example,for page 1 :
self.scrollViewNews.contentSize = CGSizeMake(constant1,constant2);
And set something else for page 2 as well .
I think you're confused about contentSize vs the paging size. The paging size is always the size of the scrollView bounds, and isn't a property you can otherwise set. That is, when you swipe left/right it will "page" by the width of the scrollview.
contentSize is the size of the virtual bounding box of all the subviews within the scrollview. This only serves to limit how far the scrollview will scroll, and for paging, how many times it will page, i.e. contentSize.width / bounds.size.width.
Assuming the scrollView isn't zoomed in/out (zoomScale = 1.0) then you need to position and size your subviews on the virtual 'page boundaries'. They can take up the full page boundary (be sized to match scrollview.bounds) or be inset. If you have some content that is larger/smaller then you'll have to decide if you want to change the scale of that content or size it up/down within the page bounds.
Yes you can dynamically set the content size of the scrollView. Also You can use this method:
self.scrollViewNews.contentSize = CGSizeMake(constant1,constant2);
Nothing wrong this method. You are seeing the blank space at bottom because you ares setting the height of the scrollView's contentSize to a larger value than it's content. That's the issue. Adjust the height according to the contents, blank space will go.
please, try to get the actual content size from the current content.
the content must be some inherited class from the UIView and it has a frame.size.width and frame.size.height property.
you can use those to set the contentSize of your UIScrollview for the current content at that time when you add the content to the UIScrollView.
Yeah. You can set the scrollView size dynamically through
scroller.contentSize = CGSizeMake(1650, 2000);
You can use the following property to set the dynamic frame for each pages
[urScrollView scrollRectToVisible:frame animated:YES];
if you are using pagingEnabled = YES for your scrollview
The below UIScrollViewDelegate delegate will adjust the page and content
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
int page = urScrollView.contentOffset.x/urScrollView.frame.size.width;
pageControl.currentPage = page;
}
//pager action
- (IBAction)changePage:(id)sender{
int page = pageControl.currentPage;
CGRect frame = urScrollView.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
[urScrollView scrollRectToVisible:frame animated:YES];
}
please look at this sample app
Try out this.
- (void)viewDidLoad
{
float sizeOfContent = 0;
UIView *lLast = [scrollView.subviews lastObject];
NSInteger wd = lLast.frame.origin.y;
NSInteger ht = lLast.frame.size.height;
sizeOfContent = wd+ht;
scrollView.contentSize = CGSizeMake(scrollView.frame.size.width, sizeOfContent);
}
So i got an imageView inside a ScrollView that should resize, which works the way i want (see a small video here: https://dl.dropbox.com/u/80699/scroll.m4v)
what i did is setting up a UIScrollViewDelegate and using the scrollViewDidScroll method to resize my image based on the scrolling offset
- (void)scrollViewDidScroll:(UIScrollView *)aScrollView
{
CGFloat scrollViewOffset = aScrollView.contentOffset.y;
if(scrollViewOffset < 0.0f) {
// postition top
CGRect imageViewRect = self.imageView.frame;
imageViewRect.origin.y = scrollViewOffset;
if(scrollViewOffset < 0.0f && scrollViewOffset >= -50.0f) {
CGFloat newBackdropHeight = kImageHeight - scrollViewOffset;
imageViewRect.size.height = newBackdropHeight;
}
self.imageView.frame = imageViewRect;
}
}
whats basically happening here is, that if the user is scrolling upwards when he is on the top (bounces enabled) the imageView expands with the scroll until a certain amount of offset(here 60px).
the problem with this is, that if i scroll very fast, the image stops resizing, but the rest of the scrollview scrolls fast down like it would normally do. then, when the scrollview snaps back, the image expands immediately and then scales down like it should (see video here: https://dl.dropbox.com/u/80699/scroll2.m4v).
with this behavior, the user-expierience is not very nice and the user sees a jumping image.
does anybody know how i could fix this?
here is a small sample project if you want to see the behavior yourself: https://dl.dropbox.com/u/80699/scroll.zip
thanks for your help!
if anything is unclear, PLEASE leave a comment
I had a quick look at your test project, and I believe the issue is that when you scroll quickly, by the time the callback is called the Y offset is greater than -50, so the image view is not resized.
I solved this by removing the inner if condition and giving the backdrop a maximum height:
if(scrollViewOffset < 0.0f) {
// postition top
CGRect imageViewRect = self.imageView.frame;
imageViewRect.origin.y = scrollViewOffset;
CGFloat newBackdropHeight = kImageHeight - MAX(scrollViewOffset,-50.0);
imageViewRect.size.height = newBackdropHeight;
self.imageView.frame = imageViewRect;
}
Hope that helps
Within my view I create a scrollview with a width of 320 and a height of 70.
Responding to the user touching a button, I expand the scrollview, so it is 380(h) x 320(w) in size.
The code for this is shown below:
CGRect scrollviewFrame = CGRectMake(0, 30, 320, 380);
[scrollView setFrame:scrollviewFrame];
[self layoutScrollImages:YES];
CGSize srect = CGSizeMake([scrollView bounds].size.width, (kNumImages * (kScrollObjHeight + 10)));
[scrollView setContentSize:srect];
The constants mentioned in the above snippet are defined as:
const CGFloat kScrollObjHeight = 80;
const NSUInteger kNumImages = 100;
As I debug this project, I can see that srect is 320 (w) x 8000 (h) in size; however my issue is the scrollable area (where the user can actually touch to scroll the scrollview) remains the same as when it was it's original size.
I'm obviously missing something, does anyone know what it is?
have created a sample project to illustrate the issue I am having, it is available here: http://dl.dropbox.com/u/9930498/ScrollViewTest.zip
The problem in your sample is you have a very odd structure for loading your views. As such the view you're adding to the DetailScrollView instance is the root view of the DetailScrollView.xib, not the scrollview itself, which I believe is what you were expecting.
Fastest way to fix your problem is to adjust the root view in DetailScrollView.xib to autoresize width and height.
A UIView cannot respond to touches that are outside of the bounds of its superview. In your example, it appears that you expand the scroll view, but the scroll view's parent is still only 100 units high.
You should imagine the scrollView as a window, where by the window I mean the frame of the scrollView, which is also the coordinates that the scrollView detects your touches. By setting the contentView as 320 (w) x 8000 (h) you only change the content of the scroll view, which is the complete area behind that window.
By expanding content view, the scrollView can scroll a broader area, but in order to detect touches in a bigger rect, you should change frame of the scroll view.
I have the UIScrollView with pagingEnabled set to YES, and programmatically scroll its content to bottom:
CGPoint contentOffset = scrollView.contentOffset;
contentOffset.y = scrollView.contentSize.height - scrollView.frame.size.height;
[scrollView setContentOffset:contentOffset animated:YES];
it scrolls successfully, but after that, on single tap its content scrolls up to offset that it has just before it scrolls down. That happens only when I programmaticaly scroll scrollView's content to bottom and then tap. When I scroll to any other offset and then tap, nothing is happened.
That's definitely not what I'd like to get. How that should be fixed?
Much thanks in advance!
Timur.
This small hack prevents the UIScrollView from scrolling when tapped. Looks like this is happening when the scroll view has paging enabled.
In your UIScrollView delegate add this method:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
scrollView.pagingEnabled = self.scrollView.contentOffset.x < (self.scrollView.contentSize.width - self.scrollView.frame.size.width);
}
This disables the paging when the scroll view reaches the right end in horizontal scrolling (my use case, you can adapt it to other directions easily).
I just figured out what causes this problem, and how to avoid it. If you having pagingEnabled set to YES on a scroll view, you must set the contentOffset to be a multiple of the scroll view's visible size (i.e. you should be on a paging boundary).
Concrete example:
If your scroll view was (say) 460 pixels high with a content area of 920, you would need to set the content offset to EITHER 0 or 460 if you want to avoid the "scroll to beginning on tap" problem.
As a bonus, the end result will probably look better since your scroll view will be aligned with the paging boundaries. :)
The following workaround did help (assume that one extends UIScrollView with a category, so 'self' refers to its instance):
-(BOOL) scrolledToBottom
{
return (self.contentSize.height <= self.frame.size.height) ||
(self.contentOffset.y == self.contentSize.height - self.frame.size.height);
}
Then, one should sometimes turn pagingEnabled off, just at the position where scroll view reaches its bottom. In the delegate (pagingEnabled is initialy on of course, since the problem occurs only when it is enabled):
-(void) scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView.pagingEnabled == YES)
{
if ([scrollView scrolledToBottom] == YES)
scrollView.pagingEnabled = NO;
}
else
{
if ([scrollView scrolledToBottom] == NO)
scrollView.pagingEnabled = YES;
}
}
This seems to be a bug:
UIScrollView doesn't remember the position
I have tested this on iOS 4.2 (Simulator) and the issue remains.
When scrolling a ScrollView I would suggest using
[scrollView scrollRectToVisible:CGRectMake(0,0,1,1) animated:YES];
Where the rect is the position you're after. (In this case the rect would be the top of the scrollview).
Changing the content offset is not the correct way of scrolling a scrollview.
I have a UIScrollView that shows vertical data, but where the horizontal component is no wider than the screen of the iPhone. The problem is that the user is still able to drag horizontally, and basically expose blank sections of the UI. I have tried setting:
scrollView.alwaysBounceHorizontal = NO;
scrollView.directionalLockEnabled = YES;
Which helps a little, but still doesn't stop the user from being able to drag horizontally. Surely there is a way to fix this easily?
scrollView.bounces = NO;
Worked for me.
That's strange, because whenever I create a scroll view with frame and content size within the bounds of the screen on either dimension, the scroll view does not scroll (or bounce) in that direction.
// Should scroll vertically but not horizontally
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)];
scrollView.contentSize = CGSizeMake(320, 1000);
Are you sure the frame fits completely within the screen and contentSize's width is not greater than the scroll view's width?
The checkbox for bounce vertically in storyboard-scrollview can simply help...
That works for me in Swift:
scrollView.alwaysBounceHorizontal = false
scrollView.bounces = false
Try setting scrollView.bounces to NO and scrollView.alwaysBounceVertical to YES.
Whether or not a view scrolls (and bounces) horizontally depends on three things:
The content size
The left and right content insets
The width of the scroll view -
If the scroll view can fit the content size plus the insets then it doesn't scroll or bounce.
Avoid horizontal bouncing like so:
scrollView.contentSize = CGSizeMake(scrollView.frame.size.width - scrollView.contentInset.left - scrollView.contentInset.right, height);
I am adding this answer because the previous ones did not take contentInset into account.
Make sure the UIScrollView's contentSize is not wider than the UIScrollView itself. In my own apps this was enough to avoid horizontal scrolling, except in cases where I got really crazy swiping in random directions (e.g., starting a scroll while the view was still decelerating).
If anyone developing for OS X is looking here, as of OS X 10.7, the solution is to set the horizontalScrollElasticity property to false/NO on the scroll view, like this:
Swift:
scrollView.horizontalScrollElasticity = false
Objective-C:
scrollView.horizontalScrollElasticity = NO
Something to keep in mind: You know there's nothing extra to see horizontally, but will your users know that? You may want a little horizontal bounce, even if there's no extra content to show horizontally. This let's the user know that their attempts to scroll horizontally are not being ignored, there's just nothing there for them to see. But, yeah, often you really don't want the bounce.
My version for webViews, a common solution:
- (void)webViewDidFinishLoad:(UIWebView *)webView {
[webView.scrollView setContentSize: CGSizeMake(webView.frame.size.width, webView.scrollView.contentSize.height)];
}
You can disable horizontal bounces like this:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
if (scrollView.contentOffset.x < 0) {
scrollView.contentOffset = CGPointMake(0, scrollView.contentOffset.y);
} else if (scrollView.contentOffset.x > scrollView.contentSize.width) {
scrollView.contentOffset = CGPointMake(scrollView.contentSize.width, scrollView.contentOffset.y);
}
}
It resets the contentOffset.x manually and won't affect the vertical bounces. It works...
In my case, i just need to set this line:
collectionView.bounces = false