We're not yet finished implementing all of the core functionality of Foundation.
NSDictionary, NSArray, NSSet and NSString are not yet implicitly convertible to Dictionary, Array, Set, and String. In order to translate between these types, we have temporarily added a protocol to these types that allows them to be converted. There is one method called bridge().
let myArray: NSArray = ["foo", "bar", "baz"].bridge()
This also means that functions like map or reduce are currently unavailable on NSDictionary and NSArray.
These limitations should hopefully be very short-term.
A fix in the compiler is needed to split out the concept of “bridgeable to Objective-C” from “bridgeable to AnyObject”. In the meantime, we have added the implementation of the _ObjectiveCBridgeable protocol to Foundation on Linux (normally it is part of the standard library).
In short: users or implementers should be careful about the implicit conversions that may be inserted automatically by the compiler. Be sure to compile and test changes on both Darwin and Linux.
The AutoreleasingUnsafeMutablePointer type is not available on Linux because it requires autorelease logic provided by the Objective-C runtime. Most often this is not needed, but does create a divergence in some APIs like NSFormatter or the funnel methods of NSDictionary, NSArray and others. In these areas, we have proposed new API (marked with Experiment:) to work around use of the type. This proposed API is subject to change as the project progresses and should not yet be considered stable.
swiftc does not order include paths. This means that build artifact module.modulemap and the installed module.modulemap will conflict with each other. To work around the issue while developing Foundation, remove /usr/local/include/CoreFoundation/module.modulemap before building.
The python & ninja build system in place is a medium-term solution. We believe a long-term building solution will come from the Swift Package Manager. However, it can not yet build dynamic libraries nor build mixed-source (C and Swift) projects.
Data pointers that are normally autoreleased such as fileSystemRepresentationWithPath or UTF8String will leak when the data is not returned from an inner value.