I'm developing an iOS app using cordova on ARMV7 architecture because I'm using a couple of plugins that doesn't support ARM64 yet.
The problem that I can't upload the update, because iTunesConnect asks me to upload 4.7-inch and 5.5-inch which are iPhone 6 and iPhone 6 plus. And at same time, I can't run my app on iPhone 6 simulator on Xcode because it must supports ARM64 to run.
Simply, use the power of Cordova command line tools, run the simulator, save your images and then upload them to iTunesConnect.
Here's how to use Cordova command line tools https://stackoverflow.com/a/22329264/183982
Also, make sure if you are trying to test on iPhone 5S, iPhone 6 or iPhone 6-plus, Xcode won't work because your app must support ARM64, so make sure to disconnect your mobile phone if it is iPhone 5s or newer.