adding_swift_to_objc_checklist.md

Checklist for adding Swift support to Objc project

1. Add (auto-generated) bridging header ProductName-Bridging-Header.h.
2. Add SWIFT_VERSION to Build Settings -> Swift Compiler - Language.
3. Fix Multiple commands produce '.../Objects-normal/x86_64/ProductName.swiftmodule' - target ProductNames should differ.
4. Set "Defines Modules" to "Yes" in Build Settings -> Packaging.
5. #import "Objective-C Generated Interface Header Name"
6. Remove #import "ProductName-Swift.h" from headers to implementation, add forward declaration to headers.

The "rules" of converting Swift names to Objc

I had such constructor in MyClass:

public override init(userDefaults: UserDefaults) {

And I wanted to call it in Objc like this:

MyClass* obj = [[MyClass alloc] initWithUserDefaults:NSUserDefaults.standardUserDefaults];

It didn't work, while this did:

@objc convenience init(userDefaults: UserDefaults)

More comments about optional value type bridging/optional reference type bridging is here