1. How to view estimated app size before pushing to app store:

In Xcode → Windows → Organizer → Archive → View Archive in Finder → Show package contents → Applications → app name

2. How to view crash logs in Xcode:

Windows → Devices → view crash logs, or click the arrow at the bottom.

3. Sprite atlas in Unity:

If a texture is not POT(power of two), it can't be compressed into ETC1, we can add it into one of the sprite atlas, a atlas sheet will always be POT so it will be compressed. Note that we need to put only the related the sprites in the same atlas, cause if one of them is called, GPU will call the whole atlas sheet, so we need to be careful for increasing draw calls.