I left some questions last week regarding the survey performance on iOS mobile devices.
The survey I am working on is quite heavy - It's about ecological monitoring data collection so it has lots of select one lists for various species and multiple csvs as well as lots of photo attachment options. The survey worked fine with new devices, but found it is hanging or crashing while opening on the older devices.
By reducing photo attachment options, it seems working better - at least the survey could be open; however it's still unclear what's limit of data/survey size that the device can handle. Is there any documentation or information that what's the device/ iOS requirement for certain size of survey? The device kept crashing had 19GB empty space. So I am not sure if it really matters of available space.
It would be the best if we could upgrade all machines (survey works well on relatively new iphones and ipads), but the team sometimes has a very limited budget. It would be beneficial to understand some limitation so that we can advise users in advance.
I wouldn't necessarily look to limitations by version of iOS, though there are some milestone versions (like iOS11, the current minimum version). There may be differences in capabilities by devices; as you would expect, later devices tend to feature better processors and more RAM (the 19GB you were referring to is storage, not RAM).
The other factor is the complexity of your form; as you place more calculations on it, the form uses more resources. There are some ways to address this, such as grouping questions that have the same relevancy requirement (place the relevant statement on the group rather than individual questions).
Thank you for your comments. It must be the complexity of my form that causes the performance issue. I will discuss with my client to remove any unnecessary questions as well as considering splitting the form into multiple pieces- current one has multiple ecological monitoring protocols, and not all of them is expected to be used at the same time.