Swallows move FAST so it’s not easy to catch them in flight. I have a few TIPS that will help you – Click on the Image strip if you want a larger size (you may need to Click twice on it to get the 100% version).
A short while ago I submitted a swallow photo for World Photography Day. I promised I would follow up with a Feeding Sequence I took and the Settings I used. Key settings are FAST shutter speed and positioning yourself side-on to the Action to have more chance of getting the bird in Focus.
The Image Strip on the Left has the details of the Settings I used and summarizes some Tips for getting Action Bird Photos.
I hope they help
The 3rd Image was actually from a Sequence Immediately after the First Sequence – my camera has 5.3 fps which is great but swallows are quick! It just happened that the second sequence had a perfect in-betweener.