I need to create a view on the iPhone that scrolls horizontally through a gallery of images. The issue is that this gallery has the potential to have 100s to 1000s of images that needs to be presented, so I would like to avoid loading them all into a single UIScrollView at once and destroying performance. I need to create a view that recycles the view objects (like UITableView) to increase performance and reduce memory overhead, but it needs to scroll in a horizontal fashion.
Any ideas? Is it possible to make UITableView operation horizontally?
Thanks!
You could use a large scrollview, and monitor for the scroll position to change. You can add images as subviews as they are coming into the actual viewable area, and remove them as they are scrolled away.
This way, you only have to have a small number of image views present at any given time, but you give the appearance of them all being "there".
You could even recycle the image views by changing their image and location so you are not creating and destroying complex objects. This is what UITableView does with cells.
It is as simple as appyling a Transform.
Here is the code. Write this in the your tableViewController init:
self.view.frame = CGRectMake(100,-5,250,350); //any Frame of your choice
CGAffineTransform trans = self.view.transform; // get current transform (i.e. portrait)
trans = CGAffineTransformRotate(trans, (M_PI / -2.0)); // rotate 90 degrees to go landscape
self.view.transform = trans; // set current transform (landscape)
But now what you need to realize is that your axis are also swapped. Any changes you make to the height will change the width (and vice versa) and any changes made to the origin.x changes the origin.y (and vice versa)
I agree with mbmcavoy, you can also take a look iPhone/iPad – AppStore like UIScrollView with paging and preview this article explains what you need about UIScrollView as well as provides a good example and source code.
Regards
Is it possible to add a UITableView horizontally? In a different orientation than the screen. Then you can use regular UITableView semantics where each row is an image that scrolls horizontally instead of vertically.
Posting an answer to this old thread because the validated answer is not correct. You may use a UITableViewController and its dequeueReusableCellWithIdentifier built-in features.
The trick is to make your tableview rotate and then make your cell rotate in the opposite direction.
in viewDidLoad you will add:
self.view.transform = CGAffineTransformMakeRotation(-M_PI_2);
And then in cellForRowAtIndexPath you would use:
cell.containerView.transform = CGAffineTransformMakeRotation(M_PI_2);
Make sure that every content of your cell is added to a container view (in this example containerView) so that you only have to rotate the container and not every cell subview.
Also please note that it will work better with cells having square dimensions, cause otherwise you may struggle with height/width computation.
I think I have the answer for you About scrolling an UITableView Horizontally:
create an UIScrollView (and disable
the vertical scroll)
put an UITableView inside the scroll
view
change the table view width as you
wish and update the
UIScrollView.contentSize as the
tableView width
Related
I have UITableView with height = 1000px, I need to set scrollable background.
I know how to set background image for tableview but in this case that background image will not be scrollable.
Right now the only idea how to do that is:
1) create scroll view with proper height (about 1000 px), and set background image for that scroll view. then set frame of UITableView as the bounds of scroll view (and disable scrolling for UITableView).
But my idea is rather bad, because I have many cells with many images on them, and in my approach all the cells will stay in memory.
What is the best way how to implement scrollable background inside tableview?
P.S.
I have tableview header of unknown height (depends on the response from server)
If it's a repeatable pattern, one way would be to split the image, repeat the middle part and show the top/bottom only when the contentOffset reaches the boundaries of contentSize. Or set the top/bottom parts only for first/last cell and the center (repeatable part) for every other.
Edit:
As I said, for a repeatable pattern:
You crop the elements you'd use for header, footer and middle
Of course, for header & footers with information in them you'd probably need bigger header/footer images:
Get the parts and assign them as backgrounds in your cellForRowAtIndexPath: method. You can do the whole thing with a single image without separating the cropped parts in different files, that's already discussed here.
There is some example code in the official docs on how to make a "synchronized" scroll view. Since a table view is a scroll view, it should work to synchronize with a table view as well. So make your background be a scroll view behind the table view, and synchronize it.
The critical step is this:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(synchronizedViewContentBoundsDidChange:)
name:NSViewBoundsDidChangeNotification
object:synchronizedContentView];
Then it's simple in your handler to match up the content offset of your background vs. the table view.
I've a scroll view which has several UIViews that shows information to the user. This scrollview supports only horizontal scrolling and when user starts scrolling from left to right or vise versa, the center view should be bigger and the previous and next views should be smaller (as shown in the below view).
I'm able to do this by changing the frames of all the views that appear on the scrollviews. But the animation is not smooth. I just want to resize the views while scrolling according to their position. Is there anyway to do this? Any help greatly appreciated.
Well you could look at these links
UIScrollview make the current Image Larger
Or I can provide a better solution to you with iCarousel. Please refer to it and I think this might help you , and its pretty easy to integrate too :)
This might be what you are looking for CGAffineTransformScale. You need to set your UIViews transformation property, for example
CGAffineTransform transformRatio = CGAffineTransformScale(CGAffineTransformIdentity, factorX, factorY);
myView.transform = transformRatio;
factorX and factorY are the values by which to scale your views width and height.
When you view starts scrolling in and out you need to set the corresponding factors.
I know that I asked a question a few minutes ago, but I want to make a few points clearer before asking for the community's help. I'm new to iOS development, close to finishing my first app. The only thing standing in my way is this UIScrollView. I simply do not understand it, and could use your help.
This is in the detail view controller of a drill-down app with a tab bar. I have approximately 8 fields (for things like phone numbers and such) drawing from a .plist. Obviously, those take up enough room that I could use a little extra real estate. I would guess that it needs to be about the size of two views vertically, but I do not understand how to allocate that sort of space to a UIScrollView. Some tutorials I have read say that you don't even need to define it in the header, which I doubt and do not understand. Additionally, I do not understand how to simply get the app to smoothly scroll up-and down only. Apple's examples have constant move cycles that flip between horizontal pictures.
I doubt it makes very much a difference, but I have an image that is in the background. I'm going to load the view on top of that.
My question is broad, so I don't expect you to take the time to sit down and write out all of the code for me (and I wouldn't ask you to). Just an outline of quick, helpful tips would help me understand how to get this view to load in the context of my project.
Many thanks!
It's fairly simple. Add a UIScrollView to your view. Add your fields and such to the scrollview. In viewDidLoad or somewhere similar, you need to set the contentSize on your scrollview. This is the "virtual" area that will be scrollable. This will generally be larger than the frame of the scrollview. In your case, you indicated it should be roughly double the width.
For instance, if you had a scrollview with a view inside, and you wanted to make sure the entire view is visible via scrolling:
self.scrollView.contentSize = self.contentView.frame.size;
//setting scrollview zoom level
self._scrollview.minimumZoomScale=0.5;
self._scrollview.maximumZoomScale=6.0;
self._scrollview.contentSize=CGSizeMake(320,500 );
you have to outlet scroll view in .h class and #property #synthesis this scroll view.then you can able to scroll up and down,if u want only vertical scrolling ,then u have to go to interface builder and uncheck the horizontal scrolling.
You can set a few settings for your scrollview to limit the scrolling to horizontal or vertical. A few important ones are:
// pseudcode here, start typing "[scrollView " then press escape to get a intelli-sense of all // the things you can set for the scrollview.
// values could be YES/NO or TRUE/FALSE, I can't remember which one but
// I think it's YES/NO. Once you start scrolling, the phone will determine
// which way you're scrolling then lock it to that direction
[scrollView setDirectionalLockEnabled:YES];
// when you slide the view, if enough of the next part of the view is visible,
// the scrollview will snap or bounce the scrollview to fit this new "page".
// think of swiping feature to navigate the iPhone home screens
// to show different "pages" of iphone apps
[scrollView setPagingEnabled:YES];
// as a safe guard, make sure the width of your scrollview fits snuggly with the content
// it is trying to display. If the width is more than necessary to display your table of
// data vertically, sometimes the scrollview will cause the
// horizontal scrolling that you don't want to happen and you get bi-directional scrolling
Just set the content size of UIScrollView after adding all the controls/button/textfields etc. for example you add 10 textfields in UIScrollview then content size of UIScrollView will be
lastTextField.frame.origin.y+lastTextField.frame.size.height+20; 20 is for margin.
That's it let me know if you want to know something more related to your app.
I'm developing an image viewer, much like the Photos App.
It's a UIScrollView with paging enabled with images loaded from the internet, so I've adapted portions of the LazyTableImages sample. The Scroll View and each ImageView inside of it have all of their autoresize mask flags set.
When I first observed how resizes were happening during rotation, it looked good, but once I started trying to interact with the scroll view, I realized that I also had to programmatically change the size of the contentView. I did that by implementing didRotateFromInterfaceOrientation: in my view controller.
[self.scrollView setContentSize:CGSizeMake(numberOfImages * portraitWidth, [scrollView bounds].size.height)];
With interaction behaving properly, I then discovered that, if I was viewing the second photo and rotated, portions of both the 1st and 2nd photos would be shown on the screen. I needed to change the contentOffset as well.
I've tried to fix this two ways - both by using the scrollRectToVisible:animated: method of UIScrollView, as well as trying to set the contentOffset property directly. And I've experimented by putting this code in implementations of both the "one-step" and "two-step" responses to changes in Orientation. For example:
-(void)didAnimateFirstHalfOfRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation {
[self.scrollView setContentOffset:CGPointMake(currentlyViewedPhotoIndex * largeImageHeight,0) animated:YES];
In all cases though, it just looks janky as hell. Either I clearly see the scroll happen, or it just jumps. Uuuuuuuuuuugly! Is there a way to do this so that it behaves exactly like the Photos app does?
What I wound up doing instead - just before rotation starts, hide the UIScrollView and create a UIImageView that contains the currently viewed image. Rotate, that image will rotate all nice and pretty, and when rotation completes remove the ImageView and unhide the Scroll View.
Update - if you're reading this today (anytime after iOS 6), use a UIPageViewController and set transitionStyle to UIPageViewControllerTransitionStyleScroll, for crissakes.
I did something slightly different when faced with the same problem. In willRotateToInterfaceOrientation:duration:, I hide all of the UIScrollView's subviews except for the currently displayed subview, and in didRotateFromInterfaceOrientation: I unhide the subviews.
I am trying to create an app with horizontal scrolling, so that one would be able to scroll horizontally through a series of images. I watched the WWDC Session 104 video on this, and while they made an interesting app, they flew through the basics of it very quickly.
I understand using the UIScrollView, and that I have to enable paging. After that they say that I should add more views as subviews of the scrollview, but I am not clear on how to do that. I am also not clear on how I add my images to those views.
As you can probably tell I am pretty new at this so any help would be appreciated.
You want to look into UIImageView. It's a view specifically for holding images.
When you add your images, you want to set their rects (probably using initWithFrame: for each UIImageView) so that:
the first image is at 0,0
the second image is at 320,0
third is at 640,0 (etc)
I.e. each image is 320 pixels right of the previous.
The final step is to set the contentSize for your UIScrollView -- this is a CGSize which describes the total size of the scroll view.
If you have 3 images, you would then set it to (320*3) * 480 using e.g.
myScrollView.contentSize = CGSizeMake(320*3, 480);
A lot of people, when they initialize the scroll view, have a for loop or similar which steps through the images they want to display. These for loops tend to look something like this:
CGFloat scrollWidth = 0.f;
for (UIImage *someImage in someNSArrayWithImages) {
UIImageView *theView = [[UIImageView alloc] initWithFrame:
CGRectMake(scrollWidth, 0, 320.f, 480.f)];
theView.image = someImage;
[myScrollView addSubview:theView];
[theView release];
scrollWidth += 320.f;
}
myScrollView.contentSize = CGSizeMake(scrollWidth, 480.f);
This way you'll get things lined up and you'll get the content size for you at the same time.
If you want to make it so that the scroll view "intelligently" scrolls to each image and stops when people slide left/right, you can do myScrollView.pagingEnabled = YES.
Hope that helps get you going.
Assuming you have "infinite" images, putting them all there at or before launch time in a huge UIScrollView will not be an option. (there is a limit to the size of a UIView)
The way I solved it: Make a UIScrollView covering the whole screen. It's content should be a UIView of 3*320 width and 480 height, extending 320px left and 320px right.
Put 3 UIImageView's in it, left, middle and right. Set paging=YES, so the uiscrollview clips to the 3 "pages" you've created.
Make sure your class is the delegate of the uiscrollview, and listen for
-(void)scrollViewDidEndDragging:(UIScrollView*)sv willDecelerate:(BOOL)notFinished
-(void)scrollViewDidEndDecelerating:(UIScrollView*)sv
-(void)scrollViewDidEndScrollingAnimation:(UIScrollView*)sv
and make the appropriate transitions on hitting paging boundaries; shift images and set ContentOffset so you're looking at the center image again.
I suggest you make this first, and only then read on...
Then you will hit on a bug, documented here UIScrollView - (bounces = NO) seems to override (pagingEnabled = YES) and here http://www.iphonedevsdk.com/forum/iphone-sdk-development/935-paging-uiscrollview.html, which makes that you cannot disable bouncing and have paging enabled at the same time. So enable bouncing, and subclass UIScrollView, overruling setContentOffset in there to prevent bouncing. (having bouncing really enabled will make for a rather unusual user experience)
Have a look at Apple's PageControl sample code. It's fairly short and easy to follow so you'll get the gist of setting up a project where multiple view controllers are loaded as you swipe horizontally.
Once you have this setup then it's the view controller's responsibility to load its own content (in your case, an image). You should make sure you understand how to load images first (using threads, etc) before you tackle paging, etc.
Think of it as two independent tasks. The view control is responsible for loading and displaying an image. The scroll view with paging just tells the appropriate view controller when to load itself (it doesn't care what the view controller does once its loaded)
Good luck!