Tired of iPhone space problems? [View all]
Simple solution, assuming you have Amazon Prime.
They (Prime) give you a good deal of space to upload your photos (unlimited for photos, limited to 5 gigabytes for videos). I've been doing this for a while now, and find it quite workable. I used to be getting space reminders from my iPhone all the time. Now it's so simple to upload photos that I hardly ever get one.
All you do is get their app, available at the Amazon site*, and upload your photos to the cloud. The app is actually pretty good and does a nice job of organizing your photos. You can then access them via your computer for editing, mailing, etc. Or you can do it with your phone. Either way, it's easy.
If you don't want to keep them there, fine--because it's so easy to download them to your computer's hard drive or other storage. That makes this a very practical solution because you'll never have to buy more space from anyone, other than your own USB, card storage, or computer hard drive.
Once you've transferred the photos to your computer, you can delete all your iPhone photos. This will free up a lot of space on your phone.
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*just put "Amazon photos" in their search engine