Call Objective C custom init function from Swift

Question

Class A is writen in Objective C and have a custom init fucntion

@interface A ()

....

@end

@implementation A

- (id)customInitImplementedInA
{
    ... 
    return self;
}

Class B inherits from Class A and uses this custom init in the following way:

@interface B : A ()

....

@end

@implementation B
+(instancetype)instanceB{
    B *b = [[B alloc] customInitImplementedInA];
    ...
    return b;
}

Now I would like to create class C writen in Swift that inharits from A and uses the same init function. How do I do that?

class C: A {
  //How do I use customInitImplementedInA here?
}

In your actual customInitImplementedInA, the method name starts with init? — OOPer
– OOPer, Commented Aug 13, 2018 at 13:22
It takes one parameter? Why don't you write the actual name in your question? Using pseudo name makes it complex. — OOPer
– OOPer, Commented Aug 13, 2018 at 13:43

jlowe · Accepted Answer · 2018-08-13 13:43:32Z

1

You should be able to do this via super.methodname syntax.

class C: A {
    init() {
        super.customInitImplementedInA()
        // Any extra initialization for C goes here.
    }
}

edited Aug 13, 2018 at 13:43

answered Aug 13, 2018 at 13:04

jlowe

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4 Comments

Luda Over a year ago

got an error for override: Initializer does not override a designated initializer from its superclass. Removed it and got an error for customInitImplementedInA: Value of type 'A' has no member 'customInitImplementedInA'

jlowe Over a year ago

My mistake. If class A does not have a base init, then you would not need the override. Is customInitImplementedInA exposed via the interface or is it private? If it's private, you will not be able to access it.

Luda Over a year ago

It is indeed exposed via the interface. Can't imagine why this error arises

jlowe Over a year ago

Does customInit have parameters and are you calling the initializer with proper swift syntax? When you do the super. does autocomplete provide anything relating to the methods from class A?

swift2geek · Accepted Answer · 2018-08-13 13:04:25Z

0

If you inherit your swift class from Obj-C than your swift clas will have obj-c init(). if you need to call it you can include it to your swift init.

 class C: A {

        var message: B?

        init(message: B) {
            super.customInitImplementedInA()

            self.message = message

        }
    }

answered Aug 13, 2018 at 13:04

swift2geek

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2 Comments

Luda Over a year ago

What is the var message: B?

swift2geek Over a year ago

its just example of your custom init. there can be any var from your C class.

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