检查 xcode 中的指定初始值设定项

Question

Is there any way to find out which initializer is the designated one in super class in Xcode?
I type super().init.. then, Xcode shows all initializers of superclass. I want to know is there any sign or symbol to point out which is the designated one?

Also a quick question. A designated initializer(DI) in subclass is allowed to only call a convenience initializer(CI) in superclass since the CI in superclass will eventually call the DI in superclass. Correct me if I'm wrong, thanks.

Answer 1

In Swift, any initializer not marked with the keyword "convenience" is a designated initializer.

And designated initializers are required to call a designated initializer in their immediate superclass, per The Swift Programming Language . They cannot call a convenience initializer.

Answer 2

For anyone new to Xcode - this confused me for a while too. The absence of the convenience keyword is what defines a designated initializer, but depending on where you look, you won't always see the 'convenience' keyword .

You can see the convenience keyword:

• on the 'Developer documentation' page for the individual initializer
• in the 'Quick help' (right click > Show quick help, or the 'Quick help' pane on the right)
• in the definition of the class in Xcode (right click > Jump to definition)

You can't see it when looking at the overview of the class in the 'Developer documentation', or in code suggestions as you type.

(Using Xcode 13.1)