Why are there so many iOS launch screen images

Question

Could someone explain why there are so many iOS launch screen images?

The launchimages module (plugin) contains 11 different sized images where as the iOS UI documentation only talks about 7.

Create launch images in the following sizes:

For iPhone 5 and iPod touch (5th generation):

640 x 1136 pixels

For other iPhone and iPod touch devices:

640 x 960 pixels

320 x 480 pixels (standard resolution)

For iPad portrait:

1536 x 2048 pixels

768 x 1024 pixels (standard resolution)

For iPad landscape:

2048 x 1536 pixels

1024 x 768 pixels (standard resolution)

iOS Human Interface Guidelines

Trigger.io has the following:

For iPad

Retina, landscape iPad devices running iOS<7

2048x1496

Retina, landscape iPad devices running iOS7

2048x1536

Non-retina, landscape iPad devices running iOS<7

1024x748

Non-retina, landscape iPad devices running iOS7

1024x768

Retina, portrait iPad devices running iOS<7

1536x2008

Retina, portrait iPad devices running iOS7

1536x2048

Non-retina, portrait iPad devices running iOS<7

768x1004

Non-retina, portrait iPad devices running iOS7

768x1024

For iPhone

Non-retina, 3.5 inch iPhone/iPod devices

320x480

Retina, 4 inch iPhone/iPod devices

640x1136

Retina, 3.5 inch iPhone/iPod devices

640x960

Answer 1

In older versions of iOS you could choose to have the status bar present or not on app launch. If it was present, you needed to take 20 pts (20px@1x, 40px@2x) off the launch images. You would only need to include one set of images, truncated or not as was appropriate for your launch options. Apparently trigger.io still recognizes the older sizes for iPad apps.