Personally, I'd say always wireframe / sketch before coding.
The reason behind this is the interface is what the users see and use. Your app's design (from a UI / UX perspective) will almost certainly come out better if you spend some time upfront on design.
As a bonus, you'll likely write less code since you'll know exactly what you're building. Without at least a (revised) sketch in place, you may end up unnecessarily generalizing methods / classes, or adding stuff that you end up not needing later.
Anyway, that's just my opinion. I at least do some sketches, with revisions, before starting an app.
Yes. Same as the development lifecycle for web apps. The UI-first approach ensures that you pay attention to how users will use your app, as opposed to how you would like to build it. It's a subtle yet significant distinction.
BTW, there are lots of free wireframing templates for mobile apps that you can use. Even pencil and paper is a good start. Then you can run those wireframes or sketches by a few potential users to get their impressions before committing to code.
As in web app development, it's easier and cheaper to change a wireframe than to change code.
The reason behind this is the interface is what the users see and use. Your app's design (from a UI / UX perspective) will almost certainly come out better if you spend some time upfront on design.
As a bonus, you'll likely write less code since you'll know exactly what you're building. Without at least a (revised) sketch in place, you may end up unnecessarily generalizing methods / classes, or adding stuff that you end up not needing later.
Anyway, that's just my opinion. I at least do some sketches, with revisions, before starting an app.