Protection of Financial Apps against repackaging

I have tried repackaging few financial apps and when I tried running their repackaged version, I found out that either it is getting crashed at the launcher activity, or at the later point it is getting crashed.

I have a doubt that how the developers of these financial apps make their app more secure against repackaging?

Is signature checking the only way, developer will use as an anti-repackaging measure or is there any other way which developer can use?

Are the developers using any existing framework which automatically makes their app more secure?