iOS 7 / Xcode 5: Access device launch images programmatically

Question

Is there any way to use the apps LaunchImage as a background in an universal iOS app without putting the same image resources in multiple places?

I wasn't able to access the LaunchImage files in Images.xcassets, so I created two new Image Sets "Background Portrait" and "Background Landscape" (since there seems to be no way to put landscape and portrait images into the same set).

While this workaround does the jobs, I would hate to include every image into the app twice. This also has a high maintenance cost.

Any advice on how to access the LaunchImage for the current device is appreciated.

GCOLaunchImageTransition must have done the job for iOS < 7.

Answer 1

You can copy/paste the following code to load your app's launch image at runtime:

// Load launch image
NSString *launchImageName;
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
{
    if ([UIScreen mainScreen].bounds.size.height == 480) launchImageName = @"[email protected]"; // iPhone 4/4s, 3.5 inch screen
    if ([UIScreen mainScreen].bounds.size.height == 568) launchImageName = @"[email protected]"; // iPhone 5/5s, 4.0 inch screen
    if ([UIScreen mainScreen].bounds.size.height == 667) launchImageName = @"[email protected]"; // iPhone 6, 4.7 inch screen
    if ([UIScreen mainScreen].bounds.size.height == 736) launchImageName = @"[email protected]"; // iPhone 6+, 5.5 inch screen
}
else if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
{
    if ([UIScreen mainScreen].scale == 1) launchImageName = @"LaunchImage-700-Portrait~ipad.png"; // iPad 2
    if ([UIScreen mainScreen].scale == 2) launchImageName = @"LaunchImage-700-Portrait@2x~ipad.png"; // Retina iPads
}
self.launchImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:launchImageName]];

Answer 2

You can use the launch images without having to include them twice. The key is that when you use an asset catalog, the file names of the images that are included in the app bundle are (sort of) standardized and may not be related to what you've named the original files.

In particular, when you use the LaunchImage image set, the files that end up in the application bundle have names like

• LaunchImage.png
• [email protected]
• [email protected]
• [email protected]
• [email protected]
• LaunchImage-700-Landscape@2x~ipad.png

etc. Note, in particular, they are not named Default.png or any variation of that. Even if that's what you called the files. Once you've dropped them in one of the wells in the asset catalog, they come out the other end with a standard name.

So [UIImage imageNamed:@"Default"] won't work because there is no such file in the app bundle. However, [UIImage imageNamed:@"LaunchImage"] will work (assuming you've filled either the iPhone Portrait 2x well or the pre iOS7 iPhone Portrait 1x well).

The documentation indicates that the imageNamed: method on UIImage should auto-magically select the correct version, but I think this only applies to image sets other than the launch image--at least I've not gotten it to work quite correctly (could just be me not doing something right).

So depending on your exact circumstances, you might need to do a little trial and error to get the correct file name. Build and run the app in the simulator and then you can always look in the appropriate subdirectory of ~/Library/Application Support/iPhone Simulator to verify what the actual file names in the app bundle are.

But again, the main point is that there is no need to include duplicates of the image files and you don't need to make any adjustments to the Copy Bundle Resources build phase.

Answer 3

Most answers require to create an image name depending on device type, scale, size etc. But as Matthew Burke pointed out, each image inside the launch image catalog will be renamed to "LaunchImage*" and therefore we are able to iterate through our launch images and find the (for the current device) appropriate image. In Objective-C it could look like this:

NSArray *allPngImageNames = [[NSBundle mainBundle] pathsForResourcesOfType:@"png"
                                        inDirectory:nil];

for (NSString *imgName in allPngImageNames){
    // Find launch images
    if ([imgName containsString:@"LaunchImage"]){
        UIImage *img = [UIImage imageNamed:imgName];
        // Has image same scale and dimensions as our current device's screen?
        if (img.scale == [UIScreen mainScreen].scale && CGSizeEqualToSize(img.size, [UIScreen mainScreen].bounds.size)) {
            NSLog(@"Found launch image for current device %@", img.description);
            break;
        }
    }
}

(Please note that this code uses the "containsString" method introduced with iOS 8. For previous iOS versions use "rangeOfString")

Answer 4

Below is the result when I test in iOS 7.0+, only portrait oritation:

3.5 inch screen: [email protected]
4.0 inch screen: [email protected]
4.7 inch screen: [email protected]
5.5 inch screen: [email protected]
iPad2          : LaunchImage-700-Portrait~ipad.png
Retina iPads   : LaunchImage-700-Portrait@2x~ipad.png

Answer 5

A Swift version of the excellent answer by Daniel Witurna that doesn't require checking against a list of all known device types or orientations.

func appLaunchImage() -> UIImage? {

        let allPngImageNames = Bundle.main.paths(forResourcesOfType: "png", inDirectory: nil)

        for imageName in allPngImageNames
        {
            // make sure that the image name contains the string 'LaunchImage' and that we can actually create a UIImage from it.

            guard
                imageName.contains("LaunchImage"), 
                let image = UIImage(named: imageName) 
                else { continue }

            // if the image has the same scale AND dimensions as the current device's screen...

            if (image.scale == UIScreen.main.scale) && (image.size.equalTo(UIScreen.main.bounds.size))
            {
                return image
            }
        }

        return nil
    }