When you are creating images to use in your iPhone app you need to create many different images sizes for the different displays in the various flavors of the iPhone. So if you have an image that’s 200px x 200px then you will also need to 2x at 100px x 100px and 1x at 50px x 50px. To complicate the issue you need to name the images with a specific naming convention so iOS knows to use the proper image resolution for the phone that the app is running on (picName.png, picName@2X.png, picName@3x.png). It’s a bit of a time consuming thing to create all of the images, resize and rename your images to all to work with your app. There a much faster and better way of doing all of this with a free app.
The app you need is called Prepo. It’s a free app that you can download for your MAC and it will automatically create the @2x and @1x conversions for each of your images and name them with the correct naming convention. This is a huge time saver if you have many image files in your application and ensures that you don’t make any typos or image size mistakes when you are creating them. You can find out more about the app and how to find it in the App store by going to their web site: http://wearemothership.com/work/prepo/
Another image tip I can give you is to always use the asset library in XCode for your images. To create a new image set first click on the images.xcassetts file in the left file solution then right click under the AppIcon and select create new image set. Once you do that name the image set to the name you want to reference the images in your project then simply drag and drop the @3x, @2x, and regular size images to the image set place holders.
Another neat quick time saving tip is that you can actually move all three images at the same time and XCode will be smart enough to know which image should go in the proper place for the @3x, @2x and regular size. This is a pretty cool tip and will also save you a bit of time when you are actually adding all of the images to your project.
I hope this post has helped you save a little bit of time when creating your images for your app. I would like to hear from you, please add your comments below!