How do I fix an iPhone app that crashes instantly every time I try to open it?

Several of my installed apps (including banking apps and social media clients) crash back to the home screen within a fraction of a second after tapping their icon. The issue persists even after closing all background apps and restarting the device.

Is this crash loop triggered by corrupted app sandboxed cache files, an outdated API library, insufficient system RAM, or SDK incompatibility following an iOS update? What is the correct sequence of steps to offload, update, or re-install the application without losing user data? For hardware or OS diagnostics, visit iphones.pk Software Diagnostics.