UITestCase.swift

//
//  UITestCase.swift
//
//  Created by Gleb Tarasov on 23/04/2018.
//

import Foundation
import XCTest
import UIKit

class UITestCase: XCTestCase {

    private func wait(forElement element: XCUIElement, exists: Bool, timeout: TimeInterval) {
        let predicate = NSPredicate(format: "exists == %@", NSNumber(value: exists))
        let e = XCTNSPredicateExpectation(predicate: predicate, object: element)
        let result = XCTWaiter().wait(for: [ e ], timeout: timeout)
        XCTAssert(result == .completed)
    }

    func wait(forWebViewElement element: XCUIElementTypeQueryProvider, timeout: TimeInterval = 20) {
        // xcode has bug, so we cannot directly access webViews XCUIElements
        // as a workaround we can check debugDesciption and parse it, that works
        let predicate = NSPredicate { obj, _ in
            guard let el = obj as? XCUIElement else {
                return false
            }
            // If element has firstMatch, than there will be description of that at the end
            // If no match - it will be ended with "FirstMatch\n"
            return !el.firstMatch.debugDescription.hasSuffix("First Match\n")
        }

        // we need to take .firstMatch, because we parse description for that
        let e = XCTNSPredicateExpectation(predicate: predicate, object: element.firstMatch)
        let result = XCTWaiter().wait(for: [ e ], timeout: timeout)
        XCTAssert(result == .completed)
    }

    func wait(forElement element: XCUIElement, timeout: TimeInterval = 20) {
        wait(forElement: element, exists: true, timeout: timeout)
    }

    func wait(elementToHide element: XCUIElement, timeout: TimeInterval = 20) {
        wait(forElement: element, exists: false, timeout: timeout)
    }

    func wait(seconds: TimeInterval) {
        Thread.sleep(forTimeInterval: seconds)
    }

    private func coordinate(forWebViewElement element: XCUIElement) -> XCUICoordinate? {
        // parse description to find its frame
        let descr = element.firstMatch.debugDescription
        guard let rangeOpen = descr.range(of: "{{", options: [.backwards]),
            let rangeClose = descr.range(of: "}}", options: [.backwards]) else {
                return nil
        }

        let frameStr = String(descr[rangeOpen.lowerBound..<rangeClose.upperBound])
        let rect = CGRectFromString(frameStr)

        // tap on the center
        let center = CGVector(dx: rect.midX, dy: rect.midY)
        let coordinate = XCUIApplication().coordinate(withNormalizedOffset: .zero).withOffset(center)
        return coordinate
    }

    func tap(onWebViewElement element: XCUIElement) {       
        // xcode has bug, so we cannot directly access webViews XCUIElements
        // as workaround we can check debugDesciption, find frame and tap by coordinate

        // wait for element to appear before tap
        wait(forWebViewElement: element)
        
        let coord = coordinate(forWebViewElement: element)
        coord?.tap()
    }

    func exists(webViewElement element: XCUIElement) -> Bool {
        return coordinate(forWebViewElement: element) != nil
    }

    func typeText(_ text: String, toWebViewField element: XCUIElement) {
        // xcode has bug, so we cannot directly access webViews XCUIElements
        // as workaround we can check debugDesciption, find frame, tap by coordinate,
        // and then paste text there
        
        // wait for element to appear before tap
        wait(forWebViewElement: element)
        
        guard let coordBeforeTap = coordinate(forWebViewElement: element) else {
            XCTFail("no element \(element)")
            return
        }
        // "typeText" doesn't work, so we paste text
        // first tap to activate field
        UIPasteboard.general.string = text
        coordBeforeTap.tap()
        // wait for keyboard to appear
        wait(forWebViewElement: XCUIApplication().keyboards.firstMatch)
        // after tap coordinate can change
        guard let coordAfterTap = coordinate(forWebViewElement: element) else {
            XCTFail("no element \(element)")
            return
        }
        // tap one more time for "paste" menu
        coordAfterTap.press(forDuration: 1)
        wait(forElement: XCUIApplication().menuItems["Paste"])

        if XCUIApplication().menuItems["Select All"].exists {
            // if there was a text - remove it, by pressing Select All and Cut
            XCUIApplication().menuItems["Select All"].tap()
            XCUIApplication().menuItems["Cut"].tap()
            // close keyboard
            XCUIApplication().toolbars.buttons["Done"].tap()
            // call this method one more time
            typeText(text, toWebViewField: element)
            return
        }

        XCUIApplication().menuItems["Paste"].tap()
        // close keyboard
        XCUIApplication().toolbars.buttons["Done"].tap()
    }
}

I'm not in the context, this was 2 years ago. But as I remember, you should be able to enter the text into the text field inside WKWebView just with XCUIElement default method:

app.textFields["username"].typeText("email@gmail.com")

So the hack in this Gist is not needed at all. But maybe I'm wrong.