CODEWITHSUNDEEP
swift
at.
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Reputation: 52510

'Int1' is not convertible to 'Bool' error with ternary operator in initializer

The following code is giving me an error in Xcode 8.2.1:

UIColor(red: redSwitch.isOn ? 1 : 0, green: greenSwitch.isOn ? 1 : 0, blue: blueSwitch.isOn ? 1 : 0 )

The error is:

'Int1' is not convertible to 'Bool'

Why is that? redSwitch.isOn works fine in an if statement condition. The Apple reference documentation says UISwitch.isOn returns Bool.

How do I get this to work?

Upvotes: 2

Views: 1541

Answers (2)

Jeff
Jeff

Reputation: 4209

Another take on this bug.

import CoreGraphics
let hit: Bool = true
let returnStroke: Bool = false
let rotation: CGFloat = (hit ? 90 : 120)
rotation *= returnStroke ? -1.0 : 1.0 // 'Int1' is not convertible to 'Bool'

The real problem is that rotation should be a variable and not a constant. Changing let to var makes the "convertible" error disappear, and the code will run.

While keeping rotation as a constant, no amount of parenthesis in the right side expression would make the correct error message appear, either. That message being "Left side of mutating operator isn't mutable..."

Upvotes: 0

Hamish
Hamish

Reputation: 80781

It's a rubbish error message, but the problem is simply that you're missing the alpha: parameter from UIColor's init(red:green:blue:alpha:) initialiser.

let color = UIColor(red: redSwitch.isOn ? 1 : 0, green: greenSwitch.isOn ? 1 : 0,
                    blue: blueSwitch.isOn ? 1 : 0, alpha: 1)

From what I can tell, the source of the weird error message seems to be the use of the ternary operator in a convenience initialiser call where you're missing one of the parameters.

A more minimal example would be:

class Foo {
    convenience init(a: Int, b: Int) {}
}

let f = Foo(a: true ? 1 : 0) // 'Int1' is not convertible to 'Bool'

I went ahead and filed a bug over this error, SR-3839.

Upvotes: 3

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