Extending generics in Swift? [duplicate]

Question

I'm trying to extend Array<T> in Swift to add a function that calls self.append. The problem is that Swift won't seem to let me do that - when I try the following code:

extension Array { mutating func AppendObj<T>(obj: T) { //... self.append(obj); } }

it says 'T' is not convertable to 'T,' which I assume means that the 'T' the underlying Array is using might be different than the T passed to AppendObj. It also won't allow me to use extension Array<T> ("use of undeclared type T").

Is it possible to extend & use generic structs/methods in Swift? Thanks!

If I may make a suggestion, don't call your method AppendObj. Instead, call it appendObj. Method names should begin with a lower case letter in Swift (and Obj-C). — Gregory Higley
– Gregory Higley, Commented Dec 21, 2014 at 20:05

drewag · Accepted Answer · 2014-06-09 03:14:57Z

2

You shouldn't specify generics for the function, it overrides the existing template. Just leave it out:

extension Array { mutating func AppendObj(obj: T) { //... self.append(obj); } }

answered Jun 9, 2014 at 3:14

drewag

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1 Comment

MatthewSot Over a year ago

That...makes perfect sense xD Thanks!

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