iTunes shows the installation size, so if you unzip your ipa file, you will get those 1.2GB. The install size on Android could also that big. Did you check that?
Usually this happens when you compressed your texture in True Color or 16 bits and the zip compression works really well i.e. on textures that have a lot of pixels with the same colors.
Possible Solutions
1) if your textures don’t require transparency, you could switch to compressed Textures (PVRTC on iOS and ETC on Android). But if the require transparency, you should not switch to compressed because transparent PVRTC can look very ugly and ETC does not support alpha.
2) I don’t know if it is possible in your project, but you could try to reduce the amount of texture by using tint or slicing them.
UPDATE 1
I currently having a similar situation and as it turns out.
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| Platform Android iOS |
|--------------------------------------------|
| APK/IPA 380MB 400 MB |
| unzipped APK/IPA 1.19 GB 1.13 GB |
| install size on device 380MB 1.15 GB |
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The difference is that iOS unzips the IPA file completely on installation and
Android contrary reads during runtime directly out of the APK, so you could argue, that is not really installed, but it is definitely another installation type.
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