Direct overhead sunlight in the middle of the day is the worst possible lighting for photography. There is very little/nothing that you can do to set correct exposure for everything in a photo. If it is an important shot to you, there are options. There is an HDR app in the app store that helps, but is nearly impossible to pull off if your subject is a person/people. It really only works for landscape photography. Another option is to expose for the subject in your shot, then take the picture to Photoshop and dodge/burn areas in your photo that are too light or dark. I'm not sure that the iP4 flahs is strong enough to effectively be used as a fill flash in harsh sun, so that is out as an option.
In the end, even the most expensive camera equipment struggles in these conditions and you can't expect a phone camera to live up to their performance levels. Besides, I've always thought that the more a photo is altered in an editing program, the more unnatural and worse it looks. Just compose the shot to your best advantage and leave well enough alone.