情景描述

我們知道，UIWebView是有一個 keyboardDisplayRequiresUserAction屬性的，默認為YES。如果設(shè)置為YES，用戶必須明確的點擊頁面上的元素或者相關(guān)聯(lián)的輸入頁面來顯示鍵盤；如果設(shè)置為NO，一個元素的焦點事件導(dǎo)致輸入視圖的顯示和自動關(guān)聯(lián)這個元素。

那么，如果我們加載一個Web頁面時，想一開始喚起鍵盤，除了web端需要設(shè)置input 的focus狀態(tài)外，我們還需要將keyboardDisplayRequiresUserAction設(shè)置為false

問題

然而，WKWebView是沒有這個屬性的，但又想做到以上效果，怎么辦呢？只能通過runtime處理了，以下是收集Stack Overflow的方法

OC版本

#import <objc/runtime.h>

@implementation WebViewInjection

+ (void)allowDisplayingKeyboardWithoutUserAction {
    Class class = NSClassFromString(@"WKContentView");
    NSOperatingSystemVersion iOS_11_3_0 = (NSOperatingSystemVersion){11, 3, 0};

    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

Swift版本

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)
        }

    }

}

原文地址

https://stackoverflow.com/questions/32449870/programmatically-focus-on-a-form-in-a-webview-wkwebview