I have a horizontal scrollview with :
[journal setPagingEnabled:YES];
I've been using a custom method to scroll to the right on the touch of a button
[journal setContentOffset:CGPointMake(320,0) animated:YES];
Is there an already existing method for working with pages and how do I find it?
Thanks,
Rd
If you're looking for something like [myScrollView scrollToPage:3], then no, there is no built in method. It's also pretty easy to roll your own if you really want something explicit. Assuming a horizontally paged UIScrollView:
- (void)scrollUIScrollView:(UIScrollView*)scrollView toPage:(NSInteger)page {
CGFloat pageWidth = scrollView.frame.size.width;
CGFloat pageHeight = scrollView.frame.size.height;
CGRect scrollTarget = CGRectMake(page * pageWidth, 0, pageWidth, pageHeight);
[scrollView scrollRectToVisible:scrollTarget animated:YES];
}
Okay, the method name is terrible, but that's the basic idea. I may be nicer in a Category on UIScrollView.
Here's a brilliant blog post on paged UIScrollView by Matt Gallagher. I used it in a project of mine, required some tweaking but otherwise was working as expected.
The UIPageControl works similar to the way that the iPhone's SpringBoard (home screen) functions.
Related
I need to create a main menu for my app with a UIScrollView. I have some images inside it that can be clicked. When I scroll the UIScrollView I need that on the background there are other two views that move creating a parallax effect.
Can someone provide me a sample code? I'm trying to work with
-(void) scrollViewDidScroll:(UIScrollView *)scrollView
but I cannot find any productive example about applying on my project.
How's this? The imageView will scroll up half as fast as the UIScrollView.
float y = scrollView.contentOffset.y;
CGRect imageFrame = self.imageView.frame;
imageFrame.origin.y = y/2;
self.imageView.frame = imageFrame;
This GitHub repository has an amazing implementation that works quite well:
https://github.com/ralfbernert/RBParallaxScrolling
Here's my test of the code, using a UIScrollView with pagination (in the front) and an image in the background:
http://clrk.it/211o3h0A053m
The bit of code that does this parallax trick works as follows:
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
if (scrollView == _scrollView) {
float speedFactor = _headerImageScrollView.contentSize.width / _scrollView.contentSize.width;
[_headerImageScrollView setContentOffset:CGPointMake(speedFactor * _scrollView.contentOffset.x, 0)];
}
}
In this code, I've got a UIScrollView that contains a UIImageView; I call this _headerImageScrollView.
In front of it, I have a second UIScrollView with pagination and the three labels. That one's called _scrollView.
I've searched and searched for a tutorial for this but none of them are what I'm looking for. I've tried Apple's sample but it is just colors and I don't know how to make it views. All I'm looking for is a screen that will page while showing the page control. Each time the scroll view pages i want it to show a completely different view. Not different text or images but a different view. A lot like the home screen of the iPhone or ESPN Scorecenter app. Please Help!
Thank you.
I created this universal solution as examples found was to complicated and this is readable for me, code should be self explanatory.
- (IBAction)changePage:(id)sender {
_pageControlUsed = YES;
CGFloat pageWidth = _scrollView.contentSize.width /_pageControl.numberOfPages;
CGFloat x = _pageControl.currentPage * pageWidth;
[_scrollView scrollRectToVisible:CGRectMake(x, 0, pageWidth, _scrollView.frame.size.height) animated:YES];
}
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView {
_pageControlUsed = NO;
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
if (!_pageControlUsed)
_pageControl.currentPage = lround(_scrollView.contentOffset.x /
(_scrollView.contentSize.width / _pageControl.numberOfPages));
}
This does the same as #ReneDohan answer without the need for variable to store state
- (IBAction)changePage:(id)sender {
CGFloat x = self.pageControl.currentPage * self.scrollView.frame.size.width;
[self.scrollView setContentOffset:CGPointMake(x, 0) animated:YES];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
if (scrollView.isDragging || scrollView.isDecelerating){
self.pageControl.currentPage = lround(self.scrollView.contentOffset.x / (self.scrollView.contentSize.width / self.pageControl.numberOfPages));
}
}
Try out this framework : https://github.com/AdrianFlorian/AFImageViewer to present images in a scroll view using a page controll to indicate the current page.
I have't added documentation yet, but you can see examples if you clone the project.
You can easily:
- download images from the internet in a separate thread by only giving an array of urls (image urls)
- give it an array of UIImage objects
- implement a delegate and manage the image for each page yourself
There is a related question: How do I use UIPageControl to create multiple views?, a really good way to do that is explained in this blog post: http://cocoawithlove.com/2009/01/multiple-virtual-pages-in-uiscrollview.html.
I've made a demo project for this question. Please visit:
https://github.com/lenhhoxung86/PageControlDemo
I've been having a very hard time finding good examples of UIScrollView. Even Apple's UIScrollView Suite I find a bit lacking.
I'm looking for a tutorial or example set that shows me how to create something similar to the iPhone Safari tab scrolling, when you zoom out from one browser window and can flick to others.
But I'm having a hard time just getting any old view showing within a scroll view. I have a view set up with an image in it, but when I add it to the scroll view, I only get a black rectangle, no matter what I put in the view I add.
Any links or code snippets would be great!
Here is a scroll view guide from Apple
The basic steps are:
Create a UIScrollView and a content view you want to put inside (in your case a UIImageView).
Make the content view a subview of the scroll view.
Set the content size of the scrollview to the frame size of the content view. This is a very important step that people often omit.
Put the scroll view in a window somewhere.
As for the paging behavior, check out UIScrollView’s pagingEnabled property. If you need to scroll by less than a whole page you’ll need to play tricks with clipsToBounds, sort of the reverse of what is happening in this StackOverflow question.
UIScrollView *scrollview = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
NSInteger viewcount= 4;
for (int i = 0; i <viewcount; i++)
{
CGFloat y = i * self.view.frame.size.height;
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, y,self.view.frame.size.width, self .view.frame.size.height)];
view.backgroundColor = [UIColor greenColor];
[scrollview addSubview:view];
[view release];
}
scrollview.contentSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height *viewcount);
For more information Create UIScrollView programmatically
New 3/26/2013
I stumbled on an easier way to do this without code (contentSize)
https://stackoverflow.com/a/15649607/1705353
UIScrollView in paging mode assumes the pages are located right next to each other, with no gap. However if you open a photo in the Photos app and swipe through photos, you can see that it has some gap between pages. I want these gaps too.
I'm looking for existing solutions if any, or for some more bizarre ideas about implementing the page gaps besides the one I have explained below. Or maybe there's some obvious easy way I am missing?
To be clear: I want the gap to only be visible while scrolling, so I cannot simply inset the page content.
My plan is to try moving the page content from inside scrollViewDidScroll callback, so that (assuming you're scrolling to the right) initially the target page is slightly offset to the right of its page boundaries, and by the time you arrive at the target page it's back at its proper location, and the source page is slightly offset to the left of its boundaries. (Or maybe instead of moving things continuously, I'll be better off shifting the offsets, say, exactly halfway between pages.)
I'm the author of the ScrollingMadness article+example that I've been referring some people to here. I've implemented progammatic zooming, and got in-photo zooming+scrolling working together with inter-photo paging. So I know how to play with UIScrollView, and am looking for the advanced stuff.
Please don't point me at TTScrollView. I've already pointed many people to it myself, but I consider it's feel too far from the native UIScrollView behaviour, and do not want to use it in my projects.
Note that this answer is quite old. The basic concept still works but
you should not be hard coding view sizes in iOS7 and 8. Even if you ignore
that advice, you should not use 480 or 330.
Have you tried making the frame of the UIScrollView slightly larger than the screen (assuming that you want to display your images fullscreen and then arranging your subviews on the same slightly-larger-than-the-screen boundaries.
#define kViewFrameWidth 330; // i.e. more than 320
CGRect scrollFrame;
scrollFrame.origin.x = 0;
scrollFrame.origin.y = 0;
scrollFrame.size.width = kViewFrameWidth;
scrollFrame.size.height = 480;
UIScrollView* myScrollView = [[UIScrollView alloc] initWithFrame:scrollFrame];
myScrollView.bounces = YES;
myScrollView.pagingEnabled = YES;
myScrollView.backgroundColor = [UIColor redColor];
UIImage* leftImage = [UIImage imageNamed:#"ScrollTestImageL.png"];
UIImageView* leftView = [[UIImageView alloc] initWithImage:leftImage];
leftView.backgroundColor = [UIColor whiteColor];
leftView.frame = CGRectMake(0,0,320,480);
UIImage* rightImage = [UIImage imageNamed:#"ScrollTestImageR.png"];
UIImageView* rightView = [[UIImageView alloc] initWithImage:rightImage];
rightView.backgroundColor = [UIColor blackColor];
rightView.frame = CGRectMake(kViewFrameWidth * 2,0,320,480);
UIImage* centerImage = [UIImage imageNamed:#"ScrollTestImageC.png"];
UIImageView* centerView = [[UIImageView alloc] initWithImage:centerImage];
centerView.backgroundColor = [UIColor grayColor];
centerView.frame = CGRectMake(kViewFrameWidth,0,320,480);
[myScrollView addSubview:leftView];
[myScrollView addSubview:rightView];
[myScrollView addSubview:centerView];
[myScrollView setContentSize:CGSizeMake(kViewFrameWidth * 3, 480)];
[myScrollView setContentOffset:CGPointMake(kViewFrameWidth, 0)];
[leftView release];
[rightView release];
[centerView release];
Apologies if this doesn't compile, I tested it in a landscape app and hand edited it back to portrait. I'm sure you get the idea though. It relies on the superview clipping which for a full screen view will always be the case.
So I don't have enough "rep" to post a comment on the answer above. That answer is correct, but there is a BIG issue to be aware of:
If you're using a UIScrollView in a viewController that's part of a UINavigationController, the navigation controller WILL resize the frame of your scrollView.
That is, you have an app that uses a UINavigationController to switch between different views. You push a viewController that has a scrollView and you create this scrollView in the viewController's -init method. You assign it a frame of (0, 0, 340, 480).
Now, go to your viewController's -viewDidAppear method, get the frame of the scrollView you created. You'll find that the width has been reduced to 320 pixels. As such, paging won't work correctly. You'll expect the scrollView to move 340 pixels but it will, instead, move 320.
UINavigationController is a bit notorious for messing with subviews. It moves them and resizes them to accommodate the navigation bar. In short, it's not a team player -- especially in this case. Other places on the web suggest that you not use UINavigationController if you need precise control over your views' size and locations. They suggest that, instead, you create your own navigationController class based on UINavigationBar.
Well that's a ton of work. Fortunately, there's an easier solution: set the frame of the scrollView in your viewController's -viewDidAppear method. At this point, UINavigationController is done messing with the frame, so you can reset it to what it should be and the scrollView will behave properly.
This is relevant for OS 3.0. I have not tested 3.1 or 2.2.1. I've also filed a bug report with Apple suggesting that they modify UINavigationController with a BOOL such as "-shouldAutoarrangeSubviews" so that we can make that class keep its grubby hands off subviews.
Until that comes along, the fix above will give you gaps in a paginated UIScrollView within a UINavigationController.
Apple has released the 2010 WWDC session videos to all members of the iphone developer program. One of the topics discussed is how they created the photos app!!! They build a very similar app step by step and have made all the code available for free.
It does not use private api either. Here is a link to the sample code download. You will probably need to login to gain access.
http://connect.apple.com/cgi-bin/WebObjects/MemberSite.woa/wa/getSoftware?code=y&source=x&bundleID=20645
And, here is a link to the iTunes WWDC page:
http://insideapple.apple.com/redir/cbx-cgi.do?v=2&la=en&lc=&a=kGSol9sgPHP%2BtlWtLp%2BEP%2FnxnZarjWJglPBZRHd3oDbACudP51JNGS8KlsFgxZto9X%2BTsnqSbeUSWX0doe%2Fzv%2FN5XV55%2FomsyfRgFBysOnIVggO%2Fn2p%2BiweDK%2F%2FmsIXj
The way to do this is like you said, a combination of a few things.
If you want a gap of 20px between your images, you need to:
First, expand your scroll view's total width by 20px and move it left by 10px.
Second, when you lay out the xLoc of your images, add 20px for each image so they're spaced 20px apart.
Third, set the initial xLoc of your images to 10px instead of 0px.
Fourth, make sure you set the content size of your scroll view to add 20px for each image. So if you have kNumImages images and each is kScrollObjWidth, then you go like this:
[scrollView setContentSize:CGSizeMake((kNumImages * (kScrollObjWidth+20)), kScrollObjHeight)];
It should work after that!
This is just a hunch, so apologies if completely wrong, but is it possible that the contentSize is just set to slightly wider than the screen width.
The correct information is then rendered within the view to the screen width and UIScrollView takes care of the rest ?
Maybe you want to try UIScrollView's contentInset property?
myScrollView.contentInset = UIEdgeInsetsMake(0, 0, 0, 10.0);
I just thought I'd add here for posterity the solution I ended up going with. For a long time I've been using Bryan's solution of adjusting the frame in -viewDidAppear, and this has worked brilliantly. However since iOS introduced multitasking I've been running into a problem where the scroll view frame gets changed when the app resumes from the background. In this case, -viewDidAppear was not being called and I couldn't find a delegate method that would be called at the right time to reverse the change. So I decided to make my scroll view a subview of my View Controller's view, and this seemed to fix the problem. This also has the advantage of not needing to use -viewDidAppear to change the frame - you can do it right after you create the scroll view. My question here has the details, but I'll post them here as well:
CGRect frame = CGRectMake(0, 0, 320, 460);
scrollView = [[UIScrollView alloc] initWithFrame:frame];
// I do some things with frame here
CGRect f = scrollView.frame;
f.size.width += PADDING; // PADDING is defined as 20 elsewhere
scrollView.frame = f;
[self.view addSubview:scrollView];
To avoid messing with UIScrollView's frame, you could subclass UIScrollView and override layoutSubviews to apply an offset to each page.
The idea is based on the following observations:
When zoomScale !=1, the offset is zero when it is at the left / right edge
When zoomScale ==1, the offset is zero when it is at the visible rect centre
Then the following code is derived:
- (void) layoutSubviews
{
[super layoutSubviews];
// Find a reference point to calculate the offset:
CGRect bounds = self.bounds;
CGFloat pageGap = 8.f;
CGSize pageSize = bounds.size;
CGFloat pageWidth = pageSize.width;
CGFloat halfPageWidth = pageWidth / 2.f;
CGFloat scale = self.zoomScale;
CGRect visibleRect = CGRectMake(bounds.origin.x / scale, bounds.origin.y / scale, bounds.size.width / scale, bounds.size.height / scale);
CGFloat totalWidth = [self contentSize].width / scale;
CGFloat scrollWidth = totalWidth - visibleRect.size.width;
CGFloat scrollX = CGRectGetMidX(visibleRect) - visibleRect.size.width / 2.f;
CGFloat scrollPercentage = scrollX / scrollWidth;
CGFloat referencePoint = (totalWidth - pageWidth) * scrollPercentage + halfPageWidth;
// (use your own way to get all visible pages, each page is assumed to be inside a common container)
NSArray * visiblePages = [self visiblePages];
// Layout each visible page:
for (UIView * view in visiblePages)
{
NSInteger pageIndex = [self pageIndexForView:view]; // (use your own way to get the page index)
// make a gap between pages
CGFloat actualPageCenter = pageWidth * pageIndex + halfPageWidth;
CGFloat distanceFromRefPoint = actualPageCenter - referencePoint;
CGFloat numOfPageFromRefPoint = distanceFromRefPoint / pageWidth;
CGFloat offset = numOfPageFromRefPoint * pageGap;
CGFloat pageLeft = actualPageCenter - halfPageWidth + offset;
view.frame = CGRectMake(pageLeft, 0.f, pageSize.width, pageSize.height);
}
}
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