These lo-fi wireframes are a great tool for UX/UI designers for hashing out details in their app designs. They come in various file types and sizes. They are blank and simply require you to place your design on the appropriate layer and there you go - Perfect lo-fi mockup. They can also be printed out and used to sketch on. Why is this useful?...One very important stage of the UX/UI design process is the ideation stage. It's an inexpensive stage that is one of the most important. Two tools that are often used in this stage are sketching and low fidelity mockups. It's very easy to allow visual design decisions to creep in before the time is right. For this reason, I've created these lo-fi iPhone wireframes. By working with lo-fi representations of a device it keeps the brain's hi-fi switch from accidentally being triggered, so the designer can fully flesh out the functionality before moving on. I hope they are useful to you!

https://creativemarket.com/Cambeetle/1277322-iPhone-Wireframes-for-Ideation-Stage