CODEWITHSUNDEEP
iosswiftuikit
dengApro
dengApro

Reputation: 4028

Swift init method error: Declaration 'init(coder:)' cannot override more than one superclass declaration

I have many custom View in my project ( UIView's subclass). And I need to override init method.

I just want to override init(frame: CGRect) method. And I don't want to write the same code init?(coder in many UIView subclasses again and again.

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

And I add an extension to UIView, then OK.

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

}

The problem occurs, when I custom UITableView class.

class Table: UITableView {

    override init(frame: CGRect, style: UITableView.Style) {
        super.init(frame: frame, style: style)
    }

Xcode tips firstly,

'required' initializer 'init(coder:)' must be provided by subclass of 'UITableView'

class Table: UITableView {

    override init(frame: CGRect, style: UITableView.Style) {
        super.init(frame: frame, style: style)
    }

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

Xcode tips secondly,

Declaration 'init(coder:)' cannot override more than one superclass declaration

How to fix it?

Upvotes: 1

Views: 733

Answers (2)

Amrit
Amrit

Reputation: 301

You can inherit your CustomTableView class from a BaseTableView Class which is a subclass of UITableView. BaseTableView class will contain both initialiser method of UITableView. Eg: 

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

    override init(frame: CGRect, style: UITableView.Style) {
        super.init(frame: frame, style: style)
    }
}

Then your custom classes are inherited from BaseTableView class with a convenience override method of init(frame:... 

class Table1: BaseTableView {
    convenience override init(frame: CGRect, style: UITableView.Style) {
        self.init(frame: frame, style: style)
    }
}

class Table2: BaseTableView {
    convenience override init(frame: CGRect, style: UITableView.Style) {
        self.init(frame: frame, style: style)
    }
}

we use convenience override init to convey that this is a convenience init that has the same signature as the designated initializer in the superclass.

Upvotes: 0

Mojtaba Hosseini
Mojtaba Hosseini

Reputation: 119716

Because convenience init and required init conflicted. You can not have more than one implementation for an initializer.

Upvotes: 0

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