Ready to use:
Two phones without root access.
Download the latest version of imToken on both phones
One of the phones open Airplane mode as a cold wallet, keep it offline always because it has your private key
imToken on the phone which is not connected to the internet is a cold wallet. And imToken on the other phone which is connected to the internet is a hot wallet.
Open the cold wallet, enter the ETH wallet and click on the address.
Open the hot wallet, click "My Profile" → "Manage your wallet" → "Add Wallet" → "ETH" → "Cold Wallet". Click the scan button in the upper right corner, scan the QR code of the cold wallet and then click "Next" to enter the Signature page.
Back to the asset page of the cold ETH wallet, and click the scan button to scan the QR code on the Signature page of the hot wallet.
Click "Next" on the hot wallet and click the scan button to scan the signature QR code on the cold wallet to authorize signature. Click “Confirm” and then it’s done.