If Apple's attributions are correct (1), there is LGPL software on iOS, for example libiconv, and even GPL software (libgcc, libstdc++), but those have linking exceptions. WebKit also is partially LGPL.

Possibly not coincidental, the latest LGPL version I could find in the 'legal' section is 2.1.

(1) they may be overly cautious, given that they mention the L4 kernel, lua, and Tiny Scheme.