Programmatically focus on a form in a webview (WKWebView)

Question

It\'s possible with UIWebView with following:

[webView setKeyboardDisplayRequiresUserAction:NO]
Call some JS function

How can you do the sa

Answer 1

Update: This solution works for iOS 13.0, 12.2, 11.* and 10.* Also, works on iPadOS 13.1

I wrote an extension (in Swift 4 for WKWebView class that adds keyboardDisplayRequiresUserAction as a computed property, just like in UIWebView.

After referring to the Apple’s official open source documents for WebKit, I came up with the following runtime swizzling:

import Foundation
import WebKit

typealias OldClosureType =  @convention(c) (Any, Selector, UnsafeRawPointer, Bool, Bool, Any?) -> Void
typealias NewClosureType =  @convention(c) (Any, Selector, UnsafeRawPointer, Bool, Bool, Bool, Any?) -> Void

extension WKWebView{
    var keyboardDisplayRequiresUserAction: Bool? {
        get {
            return self.keyboardDisplayRequiresUserAction
        }
        set {
            self.setKeyboardRequiresUserInteraction(newValue ?? true)
        }
    }

    func setKeyboardRequiresUserInteraction( _ value: Bool) {
        guard let WKContentView: AnyClass = NSClassFromString("WKContentView") else {
            print("keyboardDisplayRequiresUserAction extension: Cannot find the WKContentView class")
            return
        }
        // For iOS 10, *
        let sel_10: Selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:userObject:")
        // For iOS 11.3, *
        let sel_11_3: Selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:changingActivityState:userObject:")
        // For iOS 12.2, *
        let sel_12_2: Selector = sel_getUid("_elementDidFocus:userIsInteracting:blurPreviousNode:changingActivityState:userObject:")
        // For iOS 13.0, *
        let sel_13_0: Selector = sel_getUid("_elementDidFocus:userIsInteracting:blurPreviousNode:activityStateChanges:userObject:")

        if let method = class_getInstanceMethod(WKContentView, sel_10) {
            let originalImp: IMP = method_getImplementation(method)
            let original: OldClosureType = unsafeBitCast(originalImp, to: OldClosureType.self)
            let block : @convention(block) (Any, UnsafeRawPointer, Bool, Bool, Any?) -> Void = { (me, arg0, arg1, arg2, arg3) in
                original(me, sel_10, arg0, !value, arg2, arg3)
            }
            let imp: IMP = imp_implementationWithBlock(block)
            method_setImplementation(method, imp)
        }

        if let method = class_getInstanceMethod(WKContentView, sel_11_3) {
            let originalImp: IMP = method_getImplementation(method)
            let original: NewClosureType = unsafeBitCast(originalImp, to: NewClosureType.self)
            let block : @convention(block) (Any, UnsafeRawPointer, Bool, Bool, Bool, Any?) -> Void = { (me, arg0, arg1, arg2, arg3, arg4) in
                original(me, sel_11_3, arg0, !value, arg2, arg3, arg4)
            }
            let imp: IMP = imp_implementationWithBlock(block)
            method_setImplementation(method, imp)
        }

        if let method = class_getInstanceMethod(WKContentView, sel_12_2) {
            let originalImp: IMP = method_getImplementation(method)
            let original: NewClosureType = unsafeBitCast(originalImp, to: NewClosureType.self)
            let block : @convention(block) (Any, UnsafeRawPointer, Bool, Bool, Bool, Any?) -> Void = { (me, arg0, arg1, arg2, arg3, arg4) in
                original(me, sel_12_2, arg0, !value, arg2, arg3, arg4)
            }
            let imp: IMP = imp_implementationWithBlock(block)
            method_setImplementation(method, imp)
        }

        if let method = class_getInstanceMethod(WKContentView, sel_13_0) {
            let originalImp: IMP = method_getImplementation(method)
            let original: NewClosureType = unsafeBitCast(originalImp, to: NewClosureType.self)
            let block : @convention(block) (Any, UnsafeRawPointer, Bool, Bool, Bool, Any?) -> Void = { (me, arg0, arg1, arg2, arg3, arg4) in
                original(me, sel_13_0, arg0, !value, arg2, arg3, arg4)
            }
            let imp: IMP = imp_implementationWithBlock(block)
            method_setImplementation(method, imp)
        }
    }
}

Make sure you call property on your WKWebView like this,

let webView = WKWebView()
webView.keyboardDisplayRequiresUserAction = false

Also, make sure your HTML TextArea element has AutoFocus set to true otherwise this won't work.