In the early days of iOS development you were limited to building and debugging with the default apps that Apple shipped. Today, there are dozens of third party applications that help solve niche problems and speed up development time. Here are some of my personal favorites:
Being both a designer and developer on a project is tough. Even tougher still is having a dedicated designer and developer that do not have a common medium to share styles. PaintCode solves this problem by letting designers create visually and allowing the developer to extract the code needed to draw and animate the visual elements. Their upcoming telekinesis product looks especially useful!
Euclid: Grid / Ruler Tool
There are lots of various tools out there to measure and show grids, but what I love about Euclid is just how small and useful it is for everything. Not take up a large memory or CPU footprint is especially important to me, as I already have multiple applications open when doing mobile development.
Not exactly a tool, but what good is a tool without a toolbox? Swift Toolbox is built and maintained by us (shameless plug) and is the most widely adopted way to share and find Swift libraries.
Form lets you prototype quickly and easily and is rendered real-time on the devices you are building for. I use it heavily with PaintCode for quickly designing and prototyping application.
Whenever you are working with raster graphics, be it web/mobile/desktop you need to consider various device resolutions like retina vs non. Prepo is the absolute best tool for the job of saving assets for these various device resolutions. They even support live previews via the ipad app and iphone app!
Debugging apps is just as important as creating them, and one of the most creative and useful tools for the job is Spark Inspector. It features a 3d view to help visualize the various UI layers of your application, as well as real time UI manipulation.
Is there a tool you simply cannot live without for iOS / Swift development? Share it with us in the comments!