Graphviz for type dependencies (or uml?)

Solid for class or struct, dotted for protocol
Composition vs inheritance difference in edges? (red for inheritance, black for normal reference)
Cluster nodes of same module together in subgraphs
- submodules in sub-cluster
- edges within a module defined in cluster, between modules outside of cluster

Complexity analysis

how many types have large numbers of dependencies
cyclic dependency detection?
islands based on some root set of Files or types (no incoming dependencies from a root), declare as safe to remove

swift generated interface of bridging header, analyze types available there for edges coming into swift types
search .m/.mm files for -Swift.h imports for edges leaving swift types (references to types in generated header are not safe to delete)
? objc files are all roots as static dep analysis is not easy or feasible there with sourcekit