Custom class initialisation in swift

Question

I'm trying to implement a custom class extending UIControl in swift and can't quite work out the initialisation.

class UIRangeSlider: UIControl {
    var minimumValue: Float32
    var maximumValue: Float32

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    init(frame: CGRect, minimumValue: Float32, maximumValue: Float32) {
        self.minimumValue = minimumValue
        self.maximumValue = maximumValue
        super.init(frame: frame)
    }
}

When I try to create an instance of this class with:

var sliderFrame = CGRect(x: 20, y: 200, width: 200, height: 5)
var slider = UIRangeSlider(frame: sliderFrame, minimumValue: 1, maximumValue: 10)

I get the error:

Property 'self.minimumValue' not initialised at super.init call

What is the correct way to write this custom initialiser?

All non-optional properties must be initialized at compile time ;) — HAS
– HAS, Commented Nov 19, 2014 at 11:12

Kirsteins · Accepted Answer · 2014-11-19 11:17:01Z

1

Swift always requires any new members of class to have some kind of default value before you can call designated init.

required init(coder aDecoder: NSCoder) {
    self.minimumValue = 0.0 // some default value
    self.maximumValue = 0.0 // some default value

    super.init(coder: aDecoder)
}

answered Nov 19, 2014 at 11:17

Kirsteins

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1 Comment

N_Kraemer Over a year ago

Is it possible to alter the coder function to take more parameters? Or is there any other way to only allow initialisation with a given minimum and maximum value?

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