Freeplane - Freeplane is a powerful and free software for building mind maps.
iOS Design Kit - The newest library of native iOS templates
vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.
Fludish Sketch UI Kit - 🌱 Fluent iOS UI Kit designed for Sketch.
Linked Ideas - A macOS/iOS apps to treat ideas as links of concepts.
iOS 12 GUI - Free collection of UI components and screens of iOS 12