About the spv wallet and mobile smart contact platform by Jordan Earlz
1 how do you design the "making smart contract work on smartphones and tablets" ?
We use the a slightly extended version of the SPV protocol to accomplish this.
2 does that means do you already have the swift/java version solidity compiler and EVM?
There are two approaches. The first approach is the most simple, but also carries some limitations. In this approach there is no need for an EVM implementation. However, it is not possible to execute contracts off-chain (without spending gas). The second approach is powerful, but does require an EVM implementation. In this method you can do almost anything a full node can do except for fully validate all blocks (which a mobile wallet has no need for). You can execute contracts off-chain on the mobile device.
Although the second approach will require an EVM implementation, it is not necessarily something you will have to compile into your app yourself. We are working on an IPC interface for iOS and Android that will allow third party apps to make use of the Qtum SPV wallet through an API and thus not require storing private keys and managing signatures, and can also be used for executing EVM contract code, instead of every app needing to include their own version of the EVM
3 what's the real advantage spv protocol can bring in Qtum's so called mobile smart contract platform?
The big advantage is that it's trustless and decentralized. Using SPV a mobile wallet can interact with the Qtum network directly. In order to take down a mobile wallet's connectivity, one would have to DDoS or attack the entire Qtum network, which is extremely difficult if not impossible. This is a major advantage over a centralized wallet, which can be shut down by shutting down a single company's set of servers. Additionally in a centralized wallet it's possible for the server to report invalid transaction data if a hacker gets access to the server due to a security vulnerability