In my project i have about 100 images all tiled to display large zooms with CATiled methods. These are a lot of files that, if put in a local bundle, rapidly make the app bundle too big.
I want to load these files from a web repository, using SDWebImage or any other sdk.
Can you suggest any method to achieve this? Please keep in mid we are not talking of loading a single image, or multiple images for a UITableView, but lots of little tiled images that will be used when the user make zoom in a given view, and therefore this tiles have no UIImageview object to hold them, they are just in the bundle (now).
We are using ios7.
Thank you in advance.
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i'm having array of image urls (say count=10), i have to display the images in NSCollectionView. but the images were took lot of time to display. what is lazy loading? i'm searching for mac osx not IOS.
If your images are not downloaded you can still show your view. You just display some placeholder, or an activityIndicator instead of each image, and when each of your images finishes downloading, you replace your placeholder with the correct image. Just make sure to download your images on an background thread and perform the replacing on the main thread. I recommend using NSOperationQueue for downloading on an background thread.
Download files asynchronously .So that it wont affect the main thread.
Lazy loading is a design pattern commonly used in computer programming to defer initialization of an object until the point at which it is needed.
that is when the image is visible only it needs to be loaded.So do it that way.Collectionview and tableview populates in such a way itself
I'm developing a iOS app that is using custom UIButtons with round shape. I wanted to add Image to these buttons and would like to know if I use IB to select an image from my project, do I have to also worry about 2x retina images for retina display?. What should be the image size for both non-retina and retina devices (all iPhones (including iphone 5) and iPad including mini) when I embedded them from IB?
Is there a best resource available on the Internet to get these pngs files for buttons?
Yes you should use all the images. you should just add the images with proper names to the resources folder. And just select the non-retina image rest the compiler will take care of.
http://www.idev101.com/code/User_Interface/sizes.html
The above link will help you with the images sizes
It is easy. Goto interface builder and on the right hand panel you will see this -
All you need to do is first configure your button as custom then include a image file in your project through xcode and then you can select that image in the dropdown in background or image property.
Note that all this is possible to do through code also, its just that IB makes it interactive. Hope this helps.
I am about to launch a new app and would lik eto increase quality of the graphics. In my case the graphics is the logo and the custom buttons. I do not know if this impact Core Plot but that is also part of the package.
There is quite a few posts about this but there are still things i do not fully understand.
I am reading this quote from "amattn":
It's trivial:
1.Only include #2x images in your project.
2.Make sure those images have the #2x suffix.
The system will automatically downscale for non-retina devices.
The only exception is if you are doing manual, low level Core Graphics drawing.
You need to adjust the scale if so. 99.9% though, you don't have to worry about this.
From this post: Automatic resizing for 'non-retina' image versions
My question in regards to this is:
1. Should i do the testing on retina simulator only, as if i place a #2 grapic on
non-retina it will be too big? ...or is there an other way of doing it?
2. Should i always use a ImageView or is it OK to drag the image on the screen,
this is the logo i am talking about?
3. What about custom made buttons with images, how should i do with those?
4. What is the normal process to manage the different screen sizes, do people
add images for all displays or using this type of process?
Should i do the testing on retina simulator only, as if i place a #2 grapic on non-retina it will be too big? ...or is there an other
way of doing it?
It doesn't really matter which simulator you test on because as long as your non-retina and retina graphics are named correctly (image and image#2x) the correct image will be displayed automatically.
Should i always use a ImageView or is it OK to drag the image on the screen, this is the logo i am talking about?
When you drag and image from the project directly onto a view in interface builder you don't really see it happen but it has automatically created and image view which is containing the image your dropped in.
What about custom made buttons with images, how should i do with those?
[myButton setImage:[UIImage imageNamed:#"myFileName"]];
As shown in the above code you should always use the non-retina fle name when you reference the image a UI element should use. That was if iOS detects the device is retina it can automatically use the #2x version in its place.
What is the normal process to manage the different screen sizes, do people add images for all displays or using this type of process?
Yes, including multiple image resolutions common practice and is required for iPhone apps (not sure about iPad) to include both retina and non-retina images. But regardless of the requirements, you should definitely support both device resolutions to keep your customers happy!
I want show per page pdf in portait mode and display two pages when rotate to landscape mode on ipad . I had search on internet and can't find any solution. I thought two possible way.
1.Using webview but I don't know how to display two page in one webview in a webview.
2.Using CGPDF API read from two page and merge to one pdf file. But I think this may be very slow and not sure if this could do it .
or any other way could solve this problem? Thanks!!
I don't think you will have much success with using a UIWebView there. There's however nothing stopping you from putting two CATiledLayers into a UIView and display them next to each other. In fact, that's exactly what I did in my iOS PDF parsing framework.
Just set the contentView as the containerView, that includes both tiled layers, and they work perfectly together. Keep an eye on your memory though, I wouldn't allow them both rendering pdf at the same time, that most likely crashes your app due to low memory. (Drawing a PDF is really resource intensive)
I'm coding an application on Ipad, in a certain point of my application I present a ViewController with the presentModalViewController.
My ViewController is a UISScrollView who take the larger of the modalView and inside it I display some images, I allow pagingEnabled so I can see all my images inside the scrollView.
Sometimes I have to display more than 10 images inside the scrollView, so I have this error
RECEIVE MEMORY WARNING LEVEL=1 after this one RECEIVE MEMORY WARNING LEVEL=2 and finnaly the debugger exited due to signal 10 (Sigbus).
What can I do? is there a way to unload the image thats offscreen? or others things to do?
Thanks,
I guess you're adding all the images to the UIScrollView? Then the iPad has to keep all 10 images in memory. If they are full screen images, each of them will take up about 3 MB of memory, so you're using 30MB just to keep the 10 images in the scroll view.
You should only add the one or two images that are actually visible. Once they scroll out of sight, remove the UIImageView from your UIScrollView (and make sure you don't retain it anywhere else so it can be deallocated). When a new image scrolls into sight, add it to the UIScrollView only then.
In your UIScrollViewDelegate method -scrollViewDidScroll: get the current contentOffset and use that to calculate which images are visible.
Actually, this problem is even worse on the iPhone 3G, which can't even manage to display two full size photos (taken with it's own camera) at the same time.
If you can make the photos smaller ahead of time by resizing them (server side if you're snagging them from your own services, or client side if they're somehow generated on the device or retrieved from third party services), you should. They will load faster, and you can put more of them on the screen at once without running into memory issues.
The Three20 library has a really great photo-browsing control for the iPhone. I'm pretty sure they only have three photos around at any given time... the photo you're looking at, and the photos going forward or backwards.
http://github.com/facebook/three20
I also think there is an iPad branch of the Three20 controls (at ./tree/ipad), although I don't know if they include the photo browser or not, and haven't tried them yet myself... maybe that's an option for you if you don't want to spend a lot of time on that particular feature of your application. If the iPad photo browser isn't done maybe you could just adapt the iPhone version to suit your needs (shouldn't be hard).
If you want to bake the feature yourself, I'd take some inspiration from the UITableViewController. Your controller should come with associated datasource and delegate protocols to retrieve photos and respond to user events. The controller base class itself should reuse three UIImageViews and should shuffle those around to create the illusion that the user is scrolling through a large list.