基本SDK缺失

Question

I get the "BASE SDK Missing" when re-opeing projects. (I got the latest build of xcode, and latest SDK installed.)

It seems to be happening when I quit a project, (not exiting xcode), and re-open the project after a while. I have tried both, with and without my iPhone plugged in. I have tried to fix the problem like described here , but it does not help for me. - It just makes it even worse! (unrecognizable SDK)

The only way I have managed to get it back to normal, is to do a manual re-boot of my mac, plugged in my phone, waited until it has checked my iPhone, and then, opened xcode. Time consuming and annoying!

Why does it happen and what is the trick to fix this?

Answer 1

Your recent upgrade of Xcode likely removed the earlier SDK that your project was set to use. There are a couple of solutions for the problem. The most simple solution is to always select the "Latest" SDK in your project's settings and not select a specific option. You may be uncomfortable with the idea and want to run your app on an older device but it's important you understand that all of the newer SDKs can generate code that works on older versions of iOS. There's a separate hard to remember option for setting the deploy target. (It took me a while to learn how/why to use this but it's well worth it.)

The second option is to actually find a version of the SDK that your project is set to and attempt to reinstall it. I suggest going this route only if necessary as it's not guaranteed to work in each case. Older SDKs may or may not work in later versions of Xcode (Eg. SDK 3.0 might not work in Xcode 4.3.2) due to major changes in the toolchains. Tools like gcc/gdb are deprecated in favor of llvm/lldb. Still, you may have a valid reason for using an older SDK. You may have to fix a bug that is present only when using the older toolchain or you may need to reproduce a problem that only happens with builds generated from your build server. In many of these cases it might be easier to upgrade where the problem occurs (Eg. upgrade the tools on the build server) or downgrade your dev environment. (Install an older version of Xcode.)

The reasoning behind the frustration is that Apple highly encourages rapid adoption of it's latest tools and technologies. It creates a better product as the dev community is forced to stay current and competitive while the users are forced to maintain upgrades to ensure apps continue to work. This is in contrast with the traditional model of backward compatibility allowing developers to support revision -n of a product/platform. It is also great for business since rapid adoption of the latest often encourages purchase of newer hardware and products to get the best experience. The rapid adoption ensures the more robust software along with bug fixes, enhancements make it to the majority of consumers overall increasing their penetration in the market.

Answer 2

You have to set your target and project's base SDK to "Latest" and not an explicit option. If you choose one explicitly it seems to break if you update xcode versions.