Create Swift closure to create a UIView

user_682355 0
Viewed 526

I would like to apply DRY to the lines I'm creating in swift. How can I refactor this code so a closure is called? It resides on a viewcontroller.

var topLineView: UIView = {
    let lineView = UIView()
    lineView.layer.borderWidth = 1.0
    lineView.layer.borderColor = UIColor.lightGray.cgColor
    return lineView
}()

var bottomLineView: UIView = {
    let lineView = UIView()
    lineView.layer.borderWidth = 1.0
    lineView.layer.borderColor = UIColor.lightGray.cgColor
    return lineView
}()

var centerLineView: UIView = {
    let lineView = UIView()
    lineView.layer.borderWidth = 1.0
    lineView.layer.borderColor = UIColor.lightGray.cgColor
    return lineView
}()

I tried creating a variable but that caused an error:

let lineView = {
    let lineView = UIView()
    lineView.layer.borderWidth = 1.0
    lineView.layer.borderColor = UIColor.lightGray.cgColor
    return lineView
}

var centerLineView = lineView()

error (Unable to infer closure type etc...)

swift dry closures
2 Answers

Swift isn't able to infer the return type of your closure, so you need to tell it ahead of time that you are returning a UIView. This compiles and runs fine.

let lineView = { () -> UIView in
    let lineView = UIView()
    lineView.layer.borderWidth = 1.0
    lineView.layer.borderColor = UIColor.lightGray.cgColor
    return lineView
}
var myViewFromClosure = lineView()
var myViewFromClosure2 = lineView()
var myViewFromClosure3 = lineView()

I personally would opt for a function instead of a closure in this case, however. Like this:

func lineViewFunc() -> UIView {
    let lineView = UIView()
    lineView.layer.borderWidth = 1.0
    lineView.layer.borderColor = UIColor.lightGray.cgColor
    return lineView
}

var myViewFromFunc = lineViewFunc()
var myViewFromFunc2 = lineViewFunc()
var myViewFromFunc3 = lineViewFunc()
user_39025900

The issue with a function is I have to call it before super.init, but self does not exist yet.

user_6823550
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