I've made a image gallery with a swipe effect to skip through the uiimageviews.i am using a scrollview to do this.adding all my images in to scrollview using a for loop and am inabling the pagesEnabled=true
myScrollView.pagingEnabled = YES;
but it is taking more time in the case of multiple images.
i have a gallery page and preview page .when ever user clicking the thumb image in gallery page it will navigates to preview page .am doing the looping in preview page's view did load.but it is stucking in gallery page itself and after creating all the images inside scrollview it is showing the preview page.
my question is is there any way to avoid the time delay.??
or there is any way to load all the images after getting inside the preview page(then i can show some loading symbol there insted of stuking and showing the galllery).
There are too many images in the best thing is only to load 3 Images and then to replace the images when you are scrolling to the next. You can check out the Apple WWDC Session 104 for more information about this.
If I understand you correctly, you need to restrict your drawing to only those images currently on the screen. It takes time and memory to draw the images you can't see, and so, the more you add, the slower everything gets, for no benefit. There have been a number of good WWDC presentations on this in the last couple of years. Go to iTunes U (in iTunes) and sign up for the WWDC 2010 and WWDC 2011 videos. Look for ones on implementing scrolling and scrolling performance.
Related
I am using Fancybox. In a slideshow where the thumbnails are not reduced from larger images, and are linked to separate full-size images (that will appear in the slideshow when thumbnails are clicked), will the full-size images also pre-load with the webpage? Or only load when the slideshow is activated? My slideshows have many images, and I don't want them to load until necessary. Thanks in advance for advice!
First, you can use developer tools to easily check network activity.
The script fully loads current and previous/next slides after it is activated. Thumbnails are, hoverer, all loaded at once. This means, that if you have extremely large quantities of images, the script will load only max 3 of them and it would be better to disable thumbnails.
I have implemented a UIScrollView on the iPhone that contains 100 image slots which I fill only the currently visible page, the one before it, and the one after it as the user scrolls.
Everything works fine until we get up to image 97 or 98, the entire view disappears! The only thing I can do at that point is navigate back to the previous view.
Nothing works as far as the scroll view after this. I am not receiving any memory warnings an the rest of the app functions fine. Any ideas? Has anyone created a UIScrollView in paging mode with over 100 pages?
Rick
you might want to look into using the Three20 library.
http://three20.info/ (open source and commercial friendly license)
It has an 'image container', might save you some time on re-inventing the wheel.
I have briefly described the working of my application to under stand my Question.
I have an application, in which more than 1600 images are stored with in iPhone-Application-Document Directory.
I have a tableView on Main Screen as follows.
=>First Category
=>Second Category
=>Third Category
=>if user selects First category, Images are loaded in my ScrollView
Like
|--------------------Page View Controller-----------------|
| First Image | Second Image | Third Image | Fourth Image |
|--------------------Page View Controller-----------------|
After selecting Category, User can see - First Image From Page view Controller & others are already loaded in page View Control, user has to just scroll left - right to see the other images, but at a time user can see only one image.(that is the task of page view control)
Now Each Page has an Image View Placed in Scroll View (so user can zoom in out)
All this things work Perfectly,
Problem occurs in following situation.
=>After watching first category's images
=>User presses Back
=>Now user selects second category to view all images of second category are loaded in page view controll.
iPhone terminates the application in the given situation. (as it can't load all images to page view control)
(each image is of at-least 4 MB approximately.)
iPhone simulator works perfectly in described situation but iPhone doesn't.
iPhone terminates the application in given situation.
I think there might be memory caching problem in iPhone.
Question is how to resolve this problem?
Thanks in advance for helping me.
You are having a memory problem, you need to manage your pictures better, release them from memory when not in use. For your scroll view dont load all images at once, load at most three, this is all you need, the reason i say three is because youll have something like this
PIC ActivePic Pic
or
ActivePic Pic - here you only need 2
You load picture on each side of the active picture so when the user scrolls clipping does not occur. When you are not in the scroll view make sure to release all the images if not ull run out of memory like you have been expiriencing. Look at the sample project PageControl here http://developer.apple.com/iphone/library/samplecode/PageControl/, here they manage t he views of the scroll view in the same fashion described above.
I'm making a simple rss reader for the iPhone. The feed (http://feeds.feedburner.com/foksuk/gLTI) contains a reference to images that I want to show in my TableView.
By default, as far as I understand, the iPhone only tries to load images when they are needed: it will only load the images for the rows that are displayed. Only when the user scrolls down, it will start loading the ones that need to be displayed. Right?
Now, since the images are downloaded from the web (they are not too large, but still), the scrolling of my TableView is stuttering. This is in the emulator, so on the device itself it will only be worse.
Luckily, this specific feed only lists the latest 12 entries of the blog. So I guess I should be able to first download an cache all the images, so they can be loaded from the memory, rather than from the URL.
What is the proper approach here?
I had the same problem, where my TableView would have to download each image before it displayed the cell. Like you say, it causes a big slowdown in the scrolling speed. What you need to do is download the images in the background and then insert them into the cell when they're finished downloading. This is how the app store app does it.
This post has all you need to know, including a class file you can use straight away:
http://www.markj.net/iphone-asynchronous-table-image/
I would like to take a stack of images (or potentially an array of URLs to download images) and display them in full screen, one at a time, using user swipes to smoothly animate the next image in the stack, using the iPhone SDK. Apple's Photo.app seems to do this. Additionally, if the image has not been retrieved yet, I'd like to display the progress indicator.
Can you point me to example code and explain how this technique would be implemented?
You need to use UIScrollview's page control mechanism. Apple has plenty of sample code, including one called, strangely enough, Page Control:
http://developer.apple.com/iphone/library/samplecode/PageControl/index.html
If you want any behavior beyond that, you'll have to roll it yourself.