iOS fixes; rebasing null release

[thomassth]

Fixing issues referenced in #213, should reduce related errors pop up
Also fixed example app where it forget to check if it really had calendar permission (should be related to an issue but can't find it now?)

Also completed a rebase with upstream.
Using methods mentioned in git doc:

1. git pull Pull upstream into a separate branch
2. git rebase with the upstream branch
3. Tinker until you get a single branch, note the commit ID should follow upstream, otherwise nothing is changed.
4. git push --force your result

Git doc also suggested git pull --rebase but I couldn't figure that out.

If this keeps happening maybe I'll write contribute.md. Or just don't do this in a public git.

[nickrandolph]

@thomassth happy for contribute.md to include how to rebase. The need to rebase is quite common to ensure PRs merge cleanly without side effects. Just a note that we don't rebase develop, master, release or hotfix (unless we really have to). However, when we merge PRs in to develop, we use the rebase and merge option to keep the commit history clean