Better Mac support would be nice too. Using Swift in a larger code base in Xcode often results in long compile times, auto completion and code syntax highlighting failures and other terribleness.
I think part of the problem is that they rely too much on SourceKit, which is a rather indirect and slow way to provide basic features like syntax highlighting and auto completion. These should be built into Xcode itself. As it is now, SourceKit has to do substantial work in a short amount of time which results in frequent crashes.
The compeller's error messages could use some improvement too, I don't consider 'BAD_EXEC' to be a descriptive error at all.
Those are bugs, please report them: https://bugs.swift.org
Apple will obviously improve its Mac tools. What Swift needs is great, and even better, tools for other platforms. Will Apple keep Swift wide open if it Google gives it first class support on Android, for example?