iOS Design Kit - The newest library of native iOS templates
Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
iOS 9.3 UIKit - Most up-to-date iOS 9.3 UI Kit for Sketch and AI
Dashboard UI Kit - A modern & responsive dashboard UI kit for designers.
Chat UI kit by InVision - A beautifully minimal app UI kit (Sketch & Photoshop)
iOS 12 GUI - Free collection of UI components and screens of iOS 12