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 for iOS 13 as the method changed again:

Objective-C

#import <objc/runtime.h>

@implementation WebViewInjection

+ (void)allowDisplayingKeyboardWithoutUserAction {
    Class class = NSClassFromString(@"WKContentView");
    NSOperatingSystemVersion iOS_11_3_0 = (NSOperatingSystemVersion){11, 3, 0};
    NSOperatingSystemVersion iOS_12_2_0 = (NSOperatingSystemVersion){12, 2, 0};
    NSOperatingSystemVersion iOS_13_0_0 = (NSOperatingSystemVersion){13, 0, 0};
    char * methodSignature = "_startAssistingNode:userIsInteracting:blurPreviousNode:changingActivityState:userObject:";

    if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion: iOS_13_0_0]) {
        methodSignature = "_elementDidFocus:userIsInteracting:blurPreviousNode:activityStateChanges:userObject:";
    } else if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion: iOS_12_2_0]) {
        methodSignature = "_elementDidFocus:userIsInteracting:blurPreviousNode:changingActivityState:userObject:";
    }

    if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion: iOS_11_3_0]) {
        SEL selector = sel_getUid(methodSignature);
        Method method = class_getInstanceMethod(class, selector);
        IMP original = method_getImplementation(method);
        IMP override = imp_implementationWithBlock(^void(id me, void* arg0, BOOL arg1, BOOL arg2, BOOL arg3, id arg4) {
            ((void (*)(id, SEL, void*, BOOL, BOOL, BOOL, id))original)(me, selector, arg0, TRUE, arg2, arg3, arg4);
        });
        method_setImplementation(method, override);
    } else {
        SEL selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:userObject:");
        Method method = class_getInstanceMethod(class, selector);
        IMP original = method_getImplementation(method);
        IMP override = imp_implementationWithBlock(^void(id me, void* arg0, BOOL arg1, BOOL arg2, id arg3) {
            ((void (*)(id, SEL, void*, BOOL, BOOL, id))original)(me, selector, arg0, TRUE, arg2, arg3);
        });
        method_setImplementation(method, override);
    }
}

@end

Swift:

    func setKeyboardRequiresUserInteraction( _ value: Bool) {

        guard
            let WKContentViewClass: AnyClass = NSClassFromString("WKContentView") else {
                print("Cannot find the WKContentView class")
                return
        }

        let olderSelector: Selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:userObject:")
        let newSelector: Selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:changingActivityState:userObject:")
        let newerSelector: Selector = sel_getUid("_elementDidFocus:userIsInteracting:blurPreviousNode:changingActivityState:userObject:")
        let ios13Selector: Selector = sel_getUid("_elementDidFocus:userIsInteracting:blurPreviousNode:activityStateChanges:userObject:")

        if let method = class_getInstanceMethod(WKContentViewClass, olderSelector) {

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

        if let method = class_getInstanceMethod(wkc, newSelector) {
            self.swizzleAutofocusMethod(method, newSelector, value)
        }

        if let method = class_getInstanceMethod(wkc, newerSelector) {
            self.swizzleAutofocusMethod(method, newerSelector, value)
        }

        if let method = class_getInstanceMethod(wkc, ios13Selector) {
            self.swizzleAutofocusMethod(method, ios13Selector, value)
        }
    }

    func swizzleAutofocusMethod(_ method: Method, _ selector: Selector, _ value: Bool) {
        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, selector, arg0, !value, arg2, arg3, arg4)
        }
        let imp: IMP = imp_implementationWithBlock(block)
        method_setImplementation(method, imp)
   }

Answer 2

This Swift extension does the job and is compatible with 11.3 as well as earlier point releases.

import Foundation
import WebKit

typealias OlderClosureType =  @convention(c) (Any, Selector, UnsafeRawPointer, Bool, Bool, Any?) -> Void
typealias NewerClosureType =  @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 WKContentViewClass: AnyClass = NSClassFromString("WKContentView") else {
                print("Cannot find the WKContentView class")
                return
        }

        let olderSelector: Selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:userObject:")
        let newerSelector: Selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:changingActivityState:userObject:")

        if let method = class_getInstanceMethod(WKContentViewClass, olderSelector) {

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

        if let method = class_getInstanceMethod(WKContentViewClass, newerSelector) {

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

    }

}

Answer 3

After digging into the Webkit sources for a couple of weeks, I've managed to get this working on iOS 9 by swizzling _startAssistingNode:userIsInteracting:blurPreviousNode:userObject on WKContentView and overriding the userIsInteracting value:

Pseudo code:

swizzle_intercept("WKContentView", "_startAssistingNode:userIsInteracting:blurPreviousNode:userObject:", &hackAssist);

void hackAssist (id self, SEL _cmd, void* arg0, BOOL arg1, BOOL arg2, id arg3) {
    ((void (*)(id,SEL,void*,BOOL,BOOL,id))swizzle_interceptee(hackAssist))(self, _cmd, arg0, TRUE, arg2, arg3);
}

Cheers!

Answer 4

I had to change @Mark's answer from an extension to a subclass as Swift 4.2 gave me an "All paths through this function will call itself" warning on the keyboardDisplayRequiresUserAction getter.

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

class WebView: WKWebView {

    private var _keyboardDisplayRequiresUseraction = true

    var keyboardDisplayRequiresUserAction: Bool? {
        get {
            return _keyboardDisplayRequiresUseraction
        }
        set {
            _keyboardDisplayRequiresUseraction = newValue ?? true
            setKeyboardRequiresUserInteraction(_keyboardDisplayRequiresUseraction)
        }
    }

    private func setKeyboardRequiresUserInteraciton(_ value: Bool) {
        guard let WKContentViewClass: AnyClass = NSClassFromString("WKContentView") else {
            return print("Cannot find WKContentView class")
        }

        let oldSelector: Selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:userObject:")
        let newSelector: Selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:changingActivityState:userObject:")

        if let method = class_getInstanceMethod(WKContentViewClass, oldSelector) {
            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, oldSelector, arg0, !value, arg2, arg3)
            }
            let imp: IMP = imp_implementationWithBlock(block)
            method_setImplementation(method, imp)
        }
        if let method = class_getInstanceMethod(WKContentViewClass, newSelector) {
            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, newSelector, arg0, !value, arg2, arg3, arg4)
            }
            let imp: IMP = imp_implementationWithBlock(block)
            method_setImplementation(method, imp)
        }
    }
}

Tested on iOS 11.2 and 12.0

Answer 5

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.

Answer 6

The accepted answer no longer works in iOS 11.3, since WebKit method signature has changed. Here is a workaround (in Obj-C):

(UPDATE: Method signature has changed a few more times in iOS 12.2 and iOS 13, code below has been updated to reflect these changes)

#import <objc/runtime.h>

@implementation WebViewInjection

+ (void)allowDisplayingKeyboardWithoutUserAction {
    Class class = NSClassFromString(@"WKContentView");
    NSOperatingSystemVersion iOS_11_3_0 = (NSOperatingSystemVersion){11, 3, 0};
    NSOperatingSystemVersion iOS_12_2_0 = (NSOperatingSystemVersion){12, 2, 0};
    NSOperatingSystemVersion iOS_13_0_0 = (NSOperatingSystemVersion){13, 0, 0};
    if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion: iOS_13_0_0]) {
        SEL selector = sel_getUid("_elementDidFocus:userIsInteracting:blurPreviousNode:activityStateChanges:userObject:");
        Method method = class_getInstanceMethod(class, selector);
        IMP original = method_getImplementation(method);
        IMP override = imp_implementationWithBlock(^void(id me, void* arg0, BOOL arg1, BOOL arg2, BOOL arg3, id arg4) {
        ((void (*)(id, SEL, void*, BOOL, BOOL, BOOL, id))original)(me, selector, arg0, TRUE, arg2, arg3, arg4);
        });
        method_setImplementation(method, override);
    }
   else if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion: iOS_12_2_0]) {
        SEL selector = sel_getUid("_elementDidFocus:userIsInteracting:blurPreviousNode:changingActivityState:userObject:");
        Method method = class_getInstanceMethod(class, selector);
        IMP original = method_getImplementation(method);
        IMP override = imp_implementationWithBlock(^void(id me, void* arg0, BOOL arg1, BOOL arg2, BOOL arg3, id arg4) {
        ((void (*)(id, SEL, void*, BOOL, BOOL, BOOL, id))original)(me, selector, arg0, TRUE, arg2, arg3, arg4);
        });
        method_setImplementation(method, override);
    }
    else if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion: iOS_11_3_0]) {
        SEL selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:changingActivityState:userObject:");
        Method method = class_getInstanceMethod(class, selector);
        IMP original = method_getImplementation(method);
        IMP override = imp_implementationWithBlock(^void(id me, void* arg0, BOOL arg1, BOOL arg2, BOOL arg3, id arg4) {
            ((void (*)(id, SEL, void*, BOOL, BOOL, BOOL, id))original)(me, selector, arg0, TRUE, arg2, arg3, arg4);
        });
        method_setImplementation(method, override);
    } else {
        SEL selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:userObject:");
        Method method = class_getInstanceMethod(class, selector);
        IMP original = method_getImplementation(method);
        IMP override = imp_implementationWithBlock(^void(id me, void* arg0, BOOL arg1, BOOL arg2, id arg3) {
            ((void (*)(id, SEL, void*, BOOL, BOOL, id))original)(me, selector, arg0, TRUE, arg2, arg3);
        });
        method_setImplementation(method, override);
    }
}

@end