Comparing the NSLayoutAttribute in swift 3 - swift

Question

Following code was working well with swift 2 but it is not working with swift 3.
let constraints: NSArray = contentView.constraints as NSArray
let indexOfConstraint = constraints.indexOfObject (passingTest: { (constraint, idx, stop) in
return (constraint.firstItem ).tag == bubbleTag && (constraint.firstAttribute == NSLayoutAttribute.left || constraint.firstAttribute == NSLayoutAttribute.right)
})
I am getting following error:
Binary operator '==' cannot be applied to operands of type '_' and
'NSLayoutAttribute'
I am getting this error for following line:
constraint.firstAttribute == NSLayoutAttribute.left
How can i fix it?

Answer 1

That error message is showing only the first error that your code may cause, and you may need some more fixes to work on it.
Assuming you are using NSArray (or NSMutableArray) for constraints, why don't you declare constraints as [NSLayoutAttribute]?
With that change, you may need to fix some other parts, but the code getting the index can be written like this:
let indexOfConstraint = constraints.index {constraint in
return constraint.firstItem.tag == bubbleTag && (constraint.firstAttribute == NSLayoutAttribute.left || constraint.firstAttribute == NSLayoutAttribute.right)
}
//indexOfConstraint becomes `Int?`, so you may need to use Optional binding
if let index = indexOfConstraint {
//Do something for found case
} else {
//Do something for not-found case
}
If you cannot change the type of constraints globally, you can put this sort of code in your local code-block just before the code above.
guard let constraints = constraints as? [NSLayoutConstraint] else {
fatalError("something wrong with `constraints`")
}

Answer 2

Please, check below updated code:
let constraints: NSArray = contentView.constraints as NSArray
let indexOfConstraint = constraints.indexOfObject (passingTest:){ ( constraint, idx, stop) in
return ((constraint as AnyObject).firstItem as! UIView).tag == bubbleTag && ((constraint as AnyObject).firstAttribute == NSLayoutAttribute.left || (constraint as AnyObject).firstAttribute == NSLayoutAttribute.right)
}