I think compatibility with Objective-C and existing libraries is one of the main reasons things like fragile callbacks [weak self] strong self dance still exist

I think compatibility with Objective-C and existing libraries is one of the main reasons things like fragile callbacks [weak self] strong self dance still exists in Swift. I once got a different object returned than a Swift interface promised. That's definitely because of some kind of Objective-C library returning something completely else and still passing a compile. I like Objective-C and would still use it when I would need to use a lot of C or C++ libraries. But the compile time guarantees are simply better and forcing me to write safer code or removing a ton of boiler plate checks altogether.