Bug 1: I'm renaming a Swift class or struct. I chose to rename the file, too. Xcode renames the file in the project navigator, but apparently it does not rename the file on the file system. As a result, the file is no longer accessible from Xcode (its name is colored in red in the navigator).
Bug 2: I'm trying to rename a Swift enum. Xcode refuses with error: rename failed at <FileName>.swift:<lineNumber>:<columnNumber>
Bug 3: I'm Option+clicking on a Swift var of a custom type. Xcode pops up the dialog specifying the var's type. I'm clicking on the type, hoping I will be taken to the custom type's declaration. Instead, Xcode opens the documentation window and hangs (has to be force quit and reopened).
Now, I've been using Xcode for nearly 7 years, developing iOS apps. I don't think Xcode 8 or 9 are getting any better in terms of navigation, reliability, usefulness. 3 bugs and one restart for 5 minutes, are you joking with your developers, Apple?