I'd like to design a background image for my app. The image should fill the iPhone screen.
What image size that will work for 3G and 4G?
A) 320 x 480.
B) 640 x 960.
I prefer to use B as it will have more quality, will 3G resize the image to fit?
Thanks for any help.
Simply author both sizes and save the hi-res with a #2x suffix in the filename (like background.png and background#2x.png). iPhone 4 will use the hi-res image, older devices will stick to the ordinary one. See the docs for +[UIImage imageNamed::
This method looks in the system caches
for an image object with the specified
name and returns that object if it
exists. If a matching image object is
not already in the cache, this method
loads the image data from the
specified file, caches it, and then
returns the resulting object.
On a device running iOS 4 or later,
the behavior is identical if the
device’s screen has a scale of 1.0. If
the screen has a scale of 2.0, this
method first searches for an image
file with the same filename with an
#2x suffix appended to it. For
example, if the file’s name is button,
it first searches for button#2x. If it
finds a 2x, it loads that image and
sets the scale property of the
returned UIImage object to 2.0.
Otherwise, it loads the unmodified
filename and sets the scale property
to 1.0. See iOS Application
Programming Guide for more information
on supporting images with different
scale factors.
Also read the appropriate part of iOS Application Programming Guide.
Although it is trivial to resize the image to the proper size, you should prepare both 320×480 and 640×960 (and probably you need a 1024×768 for iPad too). In this way the system can choose the best image for that model.
Basically, you create a 320×480 background.png for the older models, and a 640×960 background#2x.png for retina display. Then load the image with
UIImage* backgroundImage = [UIImage imageNamed:#"background.png"];
in this way, the system will choose the best resolution automatically.
Related
I have a table view that displays custom cells with an image of the item. I allow the user to choose a photo from there library, which will be displayed on the cell. The image is saved in the documents directory.
I am confused on how to handle the retina vs non-retina displays.
Let's say my image is 70 x 70 pixels, should I also keep a 140 x 140 pixel version for the retina display. What's an appropriate way to handle this situation?
Yes, you should have a 70x70 px file and a 140x140 px one also. If you name your normal image "CellImage.png", you should name the retina one "CellImage#2x.png".
If you are allowing the user to choose the image from their library I am assuming that you are resizing the image before placing it in the Documents directory.
If you are sure that the images will not be shared between different devices (as in iCloud) then you can simply save the image in the correct scale and forget about it. i.e. scale the image appropriately for the current device.
You could just save the image at 140x140 and have the presentation properly scaled by the size constraints of theUIImageView.
I don't know if imageWithContentsOfFile works the same way as imageNamed method or not but when calling the imageNamed method you don't specify the file's extension but rather just the bare filename and the method attempts to select the correct file without you having to specify the decorations i.e.
Image.png
Image#2x.png
Image~iphone.png
Image#2x~iphone.png
I would like to have images for my UIButtons, screen background etc in my iPhone app.
Will it work for both Retina display and normal display if I have
ButtonImage.png and ButtonImage#2x.png
Background.png and Background#2x.png
OR, should I do any extra coding so that it works for both displays?
ButtonImage.png is looking awkward on Retina Simulator. So, I should have a higher resolution image. So... please help me.
Chandu
UIImage's imageNamed: method automatically looks up the #2x images on the retina device if they're available; no additional coding is required.
If you’re putting the image in your user interface in a .xib file, or if you use the +imageNamed: class method for UIImage, then the #2x suffix is sufficient to load Retina images.
you have nothing to do, ios do the job to choose the right one
Short Answer: Yes, that is the right way to do what you want. UIImage will figure it all out for you.
However, don't forget that you can't just copy and rename a given image (say, Background.png). You need to get an image that is the same as Background.png, but four times the resolution (that's the same as double the width and double the height). Then, you can name that Background#2x.png and everything'll be peachy keen.
Here you have to use the simple image and it will work for both, Normal display as well as retina display. You just specify simple images with ButtonImage.png & Background.png in the resource bundle and retina images ButtonImage#2x.png Background#2x.png in the resource bundle.
Now you just need to specify the simple images in the code and retina image will automatically taken when running on the device with retina screen resolution i.e. iPhone 4 and later.
backgroundImageView.image = [UIImage imageNamed:#"Background.png"];
The same code will work and when iPhone 4 with retina display it will consider the image Background#2x.png from resource bundle automatically.
Let me know if you have any other question.
That's the right thing i mean whatever you are using or describing the way,but second thing
you need to do is that allocating the position for buttons.
If you will allocating position as a constant or fix by declaring x,y coordinate then it might not work,so try to allocate position of button in dynamic way so that it will take position once retina will call it.
Thanks
I have an iPhone Xcode project that currently only contains images for retina display (twice the size as normal and with a #2x.png suffix). When I run the app on the iPhone Simulator (non retina) the images are still being displayed. Does this mean I don't need to worry about including two sets of images: retina and non-retina?
This all seems a bit odd. I would assume that no images would appear on a non retina device if there are no non-#2x files included.
Note: I have not tested my app on a non retina device. Just the simulator.
I'm pretty sure that iOS will just use the #2x and scale it down if you don't have a non-retina graphic. Although that's sub-optimal since you're letting iOS do the scaling at runtime which will be slower than including the non-retina graphic and also iOS might not do as good a job as scaling as your graphics editor of choice.
Even if it works, it's not good practice, and if you have a media heavy app definitely it would impact performance and battery life and memory foot print and ....
By the way, is it just that you don't have the 1x graphics available to you or you are concerned about your apps (download size) or ...
If you are assigning the images in Interface Builder, and you set the image property on a UIImageView to image#2x.png, for example, iOS will not know that it's a high resolution "2x" image. In fact, on a retina display, iOS will look for an image named image#2x#2x.png. Since it won't find it, it will set the scale factor of the image to 1.0.
The contentMode property (just "mode" in XCode) will decide if any scaling of the image occurs to fit the constraints of the UIImageView. You may wish to set the mode to "Aspect Fit" to get the high resolution image to scale as needed for both retina and non-retina displays. In general, the image will display as seen in Interface Builder.
If you are using UIImage's imageNamed or similar function to load the image, and just specify image (where "image.png" doesn't exist, but "image#2x.png" does), then iOS will actually find the image on a non-retina display, though the scale factor will be 1.0. As previously, you'll need to scale it to fit your view. The image will work normally on a retina device, and the scale factor will be set to 2.0, since iOS looks for a "2x" image first, and it doesn't matter if the other file exists or not.
This is from Apple's documentation on imageNamed:
On a device running iOS 4 or later, the behavior is identical if the
device’s screen has a scale of 1.0. If the screen has a scale of 2.0,
this method first searches for an image file with the same filename
with an #2x suffix appended to it. For example, if the file’s name is
button, it first searches for button#2x. If it finds a 2x, it loads
that image and sets the scale property of the returned UIImage object
to 2.0. Otherwise, it loads the unmodified filename and sets the scale
property to 1.0. See iOS App Programming Guide for more information on
supporting images with different scale factors.
If at all possible, you really should include both retina and non-retina images. Using higher-resolution images than necessary negatively affects memory and performance.
I have a few questions about screen resolution, that I'm not clear on. These questions assume they my app will be running on iOS 4.0 and up, and on either iPhone 3GS or iPhone 4.
Should the size of the splash image (default.png) be (960x640) or (480x320)?
Should the size of the app icon (Icon.png) be (57x57) or (114x114)?
What about other graphics that I may use in my app, such a graphic that represents a button? Should I always create these images for the higher resolution, and have the app scale them down? In other words, if I want a button image to be displayed on the 3GS that is 200x40 - should I create the image at 400x80, so that iPhone 4 can take advantage of it?
Thanks!
A good guide to this can be found here: http://mobile.tutsplus.com/tutorials/iphone/preparing-your-iphone-app-for-higher-resolutions/
In general you just create 2 sets of images. Your original and then a new one twice as big with #2x in the name. So for image.png at size 32x32 you would have one that is twice the resolution called image#2x.png at size 64x64. In your app just always use the image.png in Interface Builder and when loading in code.
There is no need to detect the device. These images will automatically be picked up by the OS and subbed in as necessary.
Provide both sizes (960x640 & 480x320) for the splash image using the #2x method described above
Provide both icons (57x57 & 114x114) using the #2x method
For our apps we use a combination of the #2x images and just Scaling the large images. (More information on this can be found in the above article) We use the #2x images for bar buttons, icons, etc. But for UIImageViews we often just use the Scaling. There can be a performance hit for doing this, but for most apps I'd say this is negligible. The savings in file size sometimes make scaling the only option.
Related Questions:
Retina/non-retina images in UIImageView
Making an app Retina Display friendly
You need to provide both if you want them to look nice. For example,
Default.png -> (480x320)
Amd
Default#2x.png -> (960x640)
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Closed 12 years ago.
Possible Duplicate:
How to accommodate for the different screen resolution of iPhone 4?
What does the new resolution mean for existing applications?
Do the devtools make it easy to support new resolutions without changes, if so how? what happens to apps by those developers who dont do things properly to leverage this?
What are the rules for resolution compliance for app acceptance on the app store?
According to page 75 of the latest (2010-06-04) iPhone App Programming Guide.pdf:
On devices with high-resolution
screens, the imageNamed:,
imageWithContentsOfFile:, and
initWithContentsOfFile: methods
automatically looks for a version of
the requested image with the #2x
modifier in its name. It if finds one,
it loads that image instead. If you do
not provide a high-resolution version
of a given image, the image object
still loads a standard-resolution
image (if one exists) and scales it
during drawing.
When it loads an
image, a UIImage object automatically
sets the size and scale properties to
appropriate values based on the suffix
of the image file. For standard
resolution images, it sets the scale
property to 1.0 and sets the size of
the image to the image’s pixel
dimensions. For images with the #2x
suffix in the filename, it sets the
scale property to 2.0 and halves the
width and height values to compensate
for the scale factor. These halved
values correlate correctly to the
point-based dimensions you need to use
in the logical coordinate space to
render the image.
The new OS should (As Steve Jobs stated during the keynote) detect whether or not the app is built for the new res and scale accordingly. The new resolution is just double the old, so it should be a simple scale-up on the operating system's end.
All of the current UI elements will support the new resolution once iOS4 is released, so all a developer will have to do is update their custom images.