re: why can't I purchased and download Swemos app in itunes
I don't know. Try any of the following:
1. Reboot your device.
2. Sign out of the iTunes & App Store and then sign back in.
3. Make sure that your debit/credit/gift card has enough balance to cover the app's price.
4. Go to Settings - General -Reset and then select "Reset Network Settings".
5. Contact Apple, if the above tips do not work.