IBDesignable Errors When Adding to Tests Target

Question

I have a simple UIButton subclass that implements IBDesignable with an IBInspectable var:

@IBDesignable class Button: UIButton {
    @IBInspectable var borderColor: UIColor = UIColor.whiteColor() {
        didSet { layer.borderColor = borderColor.CGColor }
    }
}

I am not using this within a framework and it is working in Interface Builder as intended, however, once I add this subclass to my Tests target, it stops rendering live and I get the following errors:

Main.storyboard: error: IB Designables: Failed to update auto layout status: dlopen(TestTests.xctest, 1): Library not loaded: @rpath/XCTest.framework/XCTest
Referenced from: TestTests.xctest
Reason: image not found

Main.storyboard: error: IB Designables: Failed to render instance of Button: dlopen(TestTests.xctest, 1): Library not loaded: @rpath/XCTest.framework/XCTest
Referenced from: TestTests.xctest
Reason: image not found

If I remove IBDesignable and the IBInspectable vars, the errors go away - unfortunately so does the live rendering in Interface Builder.

How do I test against an IBDesignable class without these errors?

Answer 1

At first, I thought this was a kind of bug in Xcode. Following is the workaround I found:

STEP 1

Mark your class and properties as public.

@IBDesignable public class Button: UIButton {
    @IBInspectable public var borderColor: UIColor = UIColor.whiteColor() {
        didSet { layer.borderColor = borderColor.CGColor }
    }

    @IBInspectable public var borderWidth:CGFloat = 0.0 {
        didSet { layer.borderWidth = borderWidth }
    }
}

STEP 2

Import your application module from your "Tests" module.

For example, assuming that your application is named MyGreatApp, in your MyGreatAppTests/MyGreatAppTests.swift:

import UIKit
import XCTest
import MyGreatApp

class MyGreatAppTests: XCTestCase {

    func testExample() {
        let btn = Button()
        btn.borderColor = UIColor.redColor()
        XCTAssertEqual(UIColor(CGColor:btn.layer.borderColor), UIColor.redColor(), "borderColor")
    }
}

You don't need to add 'Button.swift' to your "Tests" target.

STEP 3 (for Swift)

In your storyboard explicitly select the module MyGreatApp for any custom classes instead of letting Xcode use the current module.