What is the need for PNG crush in Xcode?

Question

I faced an 'PNG crush' error because of 'Default-568@2x.png'. When I unchecked compress PNG files option in the project (Project -> Target -> Build Settings -> Packaging -> Compress PNG Files) I got the error resolved.

So My Questions are:

1. Why we are using 'PNG crush' in Xcode?
2. What happen is we unchecked that option(other that compressing the png).
3. What could be the reason for that error?

Thanks in Advance.

Chahal

Answer 1

PNG crush is an optimiser for png image files. It shrinks the size of the PNG IDAT datastream by trying different levels of compression.

You might be getting an error because your Default-568@2x.png isn't really a PNG file, but some other image format saved with a .png extension.