iPhone tips and tricks: How to enable, use Truecaller on your iPhone - Check step-by-step guide
iPhone tips and tricks: To manually look up a number in the Truecaller app, you can copy a number from anywhere on your iPhone, open the Truecaller app and paste the number. You can use the Truecaller widget or you can share a number with the Truecaller app from your call log.
Enable all switches for Truecaller in iPhone Settings > Phone > Call Blocking & Identification.