Can I use the smart phone as a development board, development board and smartphones have distinction?
What are you attempting to develop?
If you're developing a product based on an SoC and selecting different parts, form factors, sensors and I/Os, a development board is generally an inexpensive way to start building and testing the software around your product and gives you easy physical access to expansion I/Os. Dev boards generally have more open software and support from the vendor (BSPs, kernels, drivers, etc) and community driven forums.
If you're developing an App or strictly software platform where you won't have to modify the kernel or OS much or at all, a smartphone is probably a better option.
Red rice 1s td is a non-open source smartphone, should according to the agreement the android open source code,but it did not open source! I think it is to use mt6582 processor. I would like to disassemble the code, but certainly not successful. Do you have any ideas, a great god
I'm not sure I understand your comment or how it relates to your first question in the thread. Could you elaborate on what you're trying to develop?
Android is Open Source Project (AOSP) is licensed under Apache 2.0. This is not a restrictive license like GPLv2 that requires changes be shared with the public. The Linux kernel underneath Android is mostly GPLv2 and, legally, companies are required to release modified code. In practice you may find that this isn't strictly observed and it takes some effort to a company to comply and release their GPLv2 kernel components. They may also have binary modules that aren't open source at all. You'd have to contact someone at the company to find out what their intentions are with their open source components.