Standard syncing doesn't always work anymore, but you have three reliable options: HOW TO INSTALL USING IPA FILES - Fannie Mae
iOS 7.1.2 is significant because it was the final destination for the iPhone 4 . The iPhone 4 was a massively popular device, but its single-core A4 processor struggled heavily with the visual flair of iOS 7. While iOS 7.0 was notoriously laggy on the iPhone 4, version 7.1.2 introduced crucial performance optimizations that made the phone usable again. ipa files for ios 712 top
Standard iTunes versions no longer support manual .ipa dragging easily. Instead, use these tools: Standard syncing doesn't always work anymore, but you
Here are some of the top sources for IPA files that are compatible with iOS 7.1.2: Standard iTunes versions no longer support manual
If you previously downloaded an app on a newer device using the same Apple ID, you can sometimes download the last compatible version for iOS 7.1.2 directly from the App Store.