How to override init method?

Question

Created Oct ’15

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I'm trying to override SKLabelNode. Below is piece of code:

import SpriteKit
class SKLabel : SKLabelNode {

    override init(fontNamed fontName: String?) {
     
        super.init(fontNamed: fontName)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

}

I've got error during execution: EXC_BAD_INSTRUCTION ....

What is wrong?

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Answer 1

DTS Engineer OP

Apple

Nov ’15

I’m not 100% sure what’s going on here but there’s seems to be some confusion about designated initialisers. SKNode’s designated initialiser is

-init

. SKLabelNode doesn’t change that,

-initWithFontNamed:

is not labelled as a designated initialiser, so that leaves its designated initialiser as

-init

. That means that you’re creating a designated initialiser that calls super’s convenience initialiser, which isn’t allowed.

As to why the compiler hasn’t complained about this at compile time, I’m not sure. Looking at the Swift interface to SKLabelNode, it shows this:

public init(fontNamed fontName: String?)

implying that Swift thinks that SKLabelNode’s designated initialiser is

-initWithFontNamed:

, which is at odds with the Objective-C header. It’s possible that Swift has some SpriteKit specific knowledge here.

You should file a bug about this, so that someone who knows more about this than I do can work out what’s going wrong. Please post your bug number, just for the record.

As to a workaround, you can make things work simply by overriding

-init

, not

-initWithFontNamed:

.

import SpriteKit 
class SKLabel : SKLabelNode { 

    override init() { 
        super.init() 
    } 

    required init?(coder aDecoder: NSCoder) { 
        fatalError("init(coder:) has not been implemented") 
    } 

}

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