So I am creating a Sprite Kit game and I want to have the same look on every device(no iPad, for now), as if it was the same scaled image.
So far I have my background images figured, 4 images for every screen size, chosen at runtime by checking the height of the screen. All my other images are designed for iPhone 6 plus, so I have #3x and #2x(66.6% of the #3x original image), that means I have iPhone 6 plus and iPhone 6 pixel perfect images.
The problem: Ran on iPhone 5/5s or 4/4s the images don't change size, they are as big as on iPhone 6, which is normal, they use the #2x. I want the images to scale by screen size. I know I have 2 options: use 4 sizes for every single image or scale the images by "screen height" / 667(iPhone 6). Both solutions are not good, because the first makes the app bigger and the second involves checking if it is iPhone 6 plus(use the #3x) and then scaling every single image, also both add a lot of code, I strive for clean code.
The first solution is acceptable, only if there is no other. Sorry for the long explanation, just want you to know what's going on.
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I am in the process of learning iOS development with XCode. I created a project to implement some of the things I've been learning and to begin learning how to manage image sizes and placement on different sized screens i.e. iPhone 8, iPhone 8+, iPad, etc. I am currently using XCode 10 Beta and I noticed that the View size on the main storyboard is half the actual screen size of any device I select to to View As:. For instance if I select View As: iPhone 8 the screen size is 375x667 instead of being 750x1334 like the actual device. I discovered this because I created a square image of 100x100px and thought I would be able to line up 7 across the screen. To my surprise the images took up twice as much screen as I had calculated.
Can anyone let me know why the screen Views in XCode are half that of actual screen size?
Do I just always assume to make my graphics half the size I would actually want them?
Edit: Here's a screenshot of what I am referring to in XCode
When I click on the empty view in the the XCode storyboard pane this is this resolution it displays for the view. Also, when I export my graphics from Illustrator the are exported with the #1x, #2x, and #3x variants. However, when I place an image in the view that is 100x100px it takes up about 1/3 of the screen instead of 1/7 of the screen as I would expect on a iPhone 8 which has a resolution of 750x1334.
Edit #2: So after playing around more with XCode I do see that the resolution for the views are in Points not pixels however, in this screenshot for a iPhone 8+ View:
I would assume with a screen resolution of 1080x1920 #3x the Point resolution would be 360x640 for an iPhone 8+ not 414x736.
It has to do with the difference between points and pixels. On the original iPhone when it was release it was 1 point per pixel but as resolution got better it became 2x pixels per point (4 pixels). Now the resolution is 3x pixels per point on some of the newer devices (9 pixels).
https://www.google.com/amp/s/blog.fluidui.com/designing-for-mobile-101-pixels-points-and-resolutions/amp/
Since the induction of 6 and 6 plus its the first time I'm starting to work on a new app. Now I'm a bit confused about the use of graphical assets for my app. See for 5/5S things were pretty simple. If I have to make an image view of lets say 180 x 30 points then my image would of 2x resolution that would be 360 x 60 and would fit pretty good inside my image view. Now since 6 and 6 plus have different screen sizes than 5/5S and different resolutions, what is the recommendation here. Should I keep the image view size same on all three devices that is 180 x 30 points. If so, what image resolutions should I be using for the 3 different devices. It would be 2x for 5/5S but what about 6 and 6 Plus and how will Xcode determine to load those automatically? Or should I use different image view size that is larger than 180 x 30 for 6 and 6 plus? Im confused here that how this all works. Help is highly appreciated. Thanks
So your image view size should always be the same amount of points on the phone. Your image will be in the assets and will be different based on the device.
So if on the non retina screen you had 180x30 and on the 5s retina you used 360x60, you would keep the same 2x(360x60) for the 6 and then 3x for the 6+(540x90)
Just add the images to your assets in the correct buckets and it should be taken care of for you.
You should keep your image view point sizes the same but you should add a new pixel resolution for all of your images (3x) which will be used for the 6+. Although the 6+ is slightly less than exactly 3x resolution, the OS does some scaling so that you can just give a 3x image and it will work correctly.
A couple of Xcode versions ago Apple added asset catalogs that make it incredibly easy to manage having multiple resolutions. Just simply drag the correct images into their correct resolution bucket and it will work automagically. Much simpler than having to append #2x and #3x to all of your images like in older versions.
The apple guides haven't helped me too much with this but I am starting to get serious about IOS development and was taken aback when I saw images go from #1x to #3x.
One source I found said they were based on sizes. For example:
If you are working on an inferred VC size and your image is 30x30 and you run that on a iPhone6 then your image should be 30x30 for #3x, 20x20 for #2x, and 10x10 for #1x.
Another source I said mentioned that it was based off the images resolution and not the size of the image.
Could someone clear this up for me and explain how to make sure my images look professional for all screens?
Thanks in advance!
When the first iPhone (and SDK) came out, all images were 1x (1 pixel of the image = 1 pixel of the screen), because that's all we had to care about. On that phone there were 166 horizontal or vertical pixels per inch (dpi). So to display an image that stretched from the left edge to the right edge, our image would need to be 320 wide (because that's what Apple told us - we didn't have to count pixels) by whatever height we wanted. Let's say 100 pixels tall. We'd name that image MyPhoto.png (because Apple told us the iPhone OS worked best with PNG images) and we'd display it.
When the iPhone 4 came out with the retina display, its retina display had 2 times the horizontal and 2 times the vertical resolution of the older phones. So now we needed higher resolution images to get the best looking interface. We were still displaying just a 2" wide image, but it would need twice the number of horizontal pixels and twice the number of vertical pixels (4 times the total number of pixels) to fill the same space. So now our image needs to be 640 pixels by 200 pixels. Since our app would still need to support the older phones as well as the new phones, we didn't want to just replace the old image with the new one. We needed a way to support both. So the old images kept the same name they had before (we didn't append "#1x") and the new images got the "#2x" filename extension to indicate they were twice the resolution. So we'd name this larger image MyPhoto#2x.png.
A common question is why not use just the higher resolution images on both old and new phones? With scaling, both appear to work great. The problem primarily is that the iPhone, especially the older phones, had very limited memory to work with. Using images that are 4 times larger than they need to be is really hard on that limited memory. That's why we had to have both 1x and 2x images in our apps.
For our sanity, we would still just use 1x while designing the interfaces. So screens remained 320 pixels wide in our code, even if we were going to display them on a retina display that was 640 pixels wide. If we wanted to draw a 1 pixel wide line on the retinal display, we'd make it half a pixel wide in our code.
With the larger screen of the iPhone 6 Plus, Apple had to pack even more pixels on the screen to maintain the high resolution customers came to expect. So now we're into 3x images. However, the iPhone 6 Plus doesn't really have three times the number of horizontal or vertical pixels. But again Apple has kept us sane by just asking us to supply "#3x" images, and it worries about scaling them down a bit on the device. As before, we still need to support smaller screen resolutions too, so we still include "#2x" and the 1x images in our apps.
So, to continue our example, the #3x image would need to be three times the width and height of the 1x image. So now we need a 960 wide by 300 pixel tall image. We'd name it MyPhoto#3x.png.
Notice that although I mentioned earlier something about a 166 dpi display, that's not really important when creating these images. In your photo editing app you don't really care if the image is 166 or 72 dpi or anything else. The only important part is the number of pixels in width and height of the final image we export.
So to answer your question (hopefully), you'll want to include all three of these images in your iPhone compatible apps. You can skip the #3x image for iPad-only apps, because there's no 3x screen yet for the iPad. But continue to think only in the 1x size when working in Interface Builder and code.
For example, now to display a 1 pixel wide line on the iPhone 6 Plus, you'd draw a 0.33 wide line rather than a 1 point line. Of course, you still want to support all of the other screen resolutions too, so you'd use code like this to set your line width:
let lineWidth = 1.0 / UIScreen.mainScreen().scale
This will give you 1.0 for the non-retinal iPhones, 0.5 for the iPhone 4, 5 & 6, and 0.33 for the iPhone 6 Plus.
I'm building an app that designers only gave me one canvas size for (9x16 aspect ratio at 1242x2208). I started an app that doesn't fully leverage the iPhone 6+'s screen space. Instead, all devices will use the same layout and assets. I did this by removing the #3x launch screen image. The goal is to use the same point system for all devices (320x568 - including for iPhone 4S - the 320x568 will be in a scroll view to fit all the content since the app is designed for 9x16 aspect and the 4S is not).
With that said, for simplicity of the question, lets say I have a full screen image (320x568 points). What are the 3 necessary pixel resolutions I need for 1x, 2x, and 3x?
When I use an app like Prepo that takes a 3x image and scales it down to 2x and 1x automatically for me, this is what happens:
I add a 3x asset at 1242x2208. It spits out:
#2x with px dimensions of 828x1472
#1x with px dimensions of 414x736
That doesn't seem right to me, but then again the whole iOS retina resolutions thing confuses me quite a bit. Shouldn't the 1x resolution end up being 320x568?
It may be that you are mentally confusing apples with oranges. Let's say you have an app that is to run on both iPhone 4s and iPhone 6 Plus (the extremes). Then you have two concerns:
Resolution. The 4s screen has 2 pixels per point, while the 6 Plus screen has 3 pixels per point. Images must come in a 3x size for the 6 Plus and a 2x size for the 4s in order to look good on both screens. This is something that the Asset Catalog will help you with.
Layout. The two screens have different sizes and different proportions. Things will need to grow and shrink in order to fit nicely and look good on both. This is something that Auto Layout (constraints) will help you with.
The two things are both involved where images are to be displayed on the screen, but in two different ways. You will have different resolution images, and they will be displayed in differently sized UIImageViews that adjust the image's display size.
To support iOS 7 to 8 on universal devices, I have to make 4 copies of the same image in different size.
For the iPhones
image#2x.png (iphone 4s,5,5s,6)
image#3x.png (iphone 6+)
For the iPads
image.png (ipad 2, ipad mini 1)
image#2x.png (ipad 3, 4, ipad mini 2, ipad Air)
The images are really bloating the app size.
Is it ok to just use 1 image size, the largest one of the set and scale to fit in the uiimageview and use the image view to scale down the image on the smaller screens?
imageView.contentMode = UIViewContentModeScaleAspectFit;
or is it absolutely necessary to have all 4 copies at different sizes?
It works on all the devices on the simulator and on a retina iPad 3, but I have no way of actual testing on other devices and am afraid that the images may not display.
Has anyone tried using 1 large image instead of the set of copies?
Yes, you can theoretically use the largest resolution image and have the UIImageView scale the image down using mode Aspect Fit.
The only drawback is the older phones that don't support retina also are less performant. For example, when using images on cells of a UITableView and scrolling, the device has to load the large image, then scale the image down, and scroll it at the same time, and it will stutter on old, slower devices.
So, perhaps just use multiple images in list views (should just be thumbnails and are tiny anyway, or just use the smaller images here), but don't worry about larger images that stay on the screen and don't scroll.
Make sure you load images in list views using methods that allow caching like imageNamed:.
As long as you take into consideration the performance penalties involved in scaling down the images, you can use just the largest image and scale it down to fit.
By the way, yes I've used this technique in real live apps in the App Store.
Another technique I've seen is to include lower quality images (1x or 2x) and if you run it on a higher resolution device (2x or 3x), automatically download high resolution images from the web. Maybe be nice about it and only download them on wifi.