Your screen isn't calibrated. I don't know if you can calibrate an iPad because I don't have one, but you can certainly use your favorite search engine to find out if this is possible.
Not so. Unedited the image looks ok. When I apply changes, it gets the green cast.
The only way the gray areas of the histogram can show the same green cast is if the monitor/screen isn't properly calibrated.
Booth images are screendumps from the iPad.
The image that appears green on the iPad is perfectly neutral on my calibrated monitor, which was confirmed by opening it in Photoshop - all three channels are identical.
The other (top) image is magenta on my screen, and Photoshop reveals higher values for red and blue, which does give a magenta cast.
If it turns out that you can't calibrate the iPad, you will have to live with the green cast.
Here's a screenshot from my screen:
Your screen isn't calibrated. I don't know if you can calibrate an iPad
I learn something new every day.
Apparently you can calibrate an iPad - if you have a Spyder colorimeter