Had this problem. 1st time user of Admob iOS as well.

This is how I solved it.

1. Go to your Project
2. Targes
3. Build Settings
4. Click 'All' and 'Levels' (so you get the same view as the screenshot)
5. On 'Search Paths' -> Go to 'Always Search User Paths' and change it to 'Yes' (see the boxed on screenshot) (mine was blank when I did mine)
6. On 'Framework Search Paths' clicked the option (boxed on screenshot) and add/change the setting to $(inherited)
7. Clean and Build your App

Got the solution from this answer: http://stackoverflow.com/a/26445806/2365714

Had this problem. 1st time user of Admob iOS as well.

This is how I solved it.

1. Go to your Project
2. Targes
3. Build Settings
4. Click 'All' and 'Levels' (so you get the same view as the screenshot)
5. On 'Search Paths' -> Go to 'Always Search User Paths' and change it to 'Yes' (see the boxed on screenshot) (mine was blank when I did mine)
6. On 'Framework Search Paths' clicked the option (boxed on screenshot) and add/change the setting to $(inherited)
7. Clean and Build your App

Got the solution from this answer: https://stackoverflow.com/a/26445806/2365714