I believe you all know that the software downloaded from the App Store can only be the latest version, can not download the old version, now with the software version of the update, it needs a higher firmware version. But if your device is an older version of the system, how can you download it to the compatibility software?
Here we take the iphone 4S for example, which is equipped with iOS7.1.1 firmware. But what if you want to download software that supports only iOS8?
As an example of a "1password" that requires more than 8 firmware, we will be prompted to upgrade the firmware as shown in the above illustration.
But don't worry, just click "Get" on your computer's iTunes to download it, not necessarily download it, just let Apple know you've already purchased the software.
Back on the phone, into the App Store-update-purchased item, the "1password" that was purchased on the computer-side iTunes appears in the list.
Then directly click on the right side similar to the "Cloud Download" button to download, it will prompt you if the firmware is too low to download a compatible old version, click to download.
In this way, an older version of 1Password that is compatible with your phone's firmware is downloaded to your phone.
Precautions:
This method is effective for all devices, including iphone6/6p with a minimum of 8 firmware;
The old version of the method download can only be used for software required firmware larger than your device's firmware;
If your device firmware is lower than the firmware required by any historical version of the software, the method is not valid;
If your device firmware is greater than the firmware required for the existing version of the software, you cannot download any historical version;
If your device has jailbreak, then you can install any historical version at your whim.
