Processing of JavaScript (Alert, Confirm, Prompt) in WKWebView

WKWebView by yourself WKUIDelegatenot displayed on the screen, such as the following as long as they do not write the code by specifying, ignores the request from the JavaScript.

I wrote the code for the purpose that you use only the following WKUIDelegate.

If the iOS8 when you create a new in Xcode Single View Applicationto create a template, ViewController.mplease try because it moves by simply copy and paste to.

//
//  ViewController.m
//  MyWKWebView
//
//  Created by vishnu on 6/6/17.
//  Copyright (c) 2017 vishnu. All rights reserved.
//

#import "ViewController.h"
#import <WebKit/WebKit.h>

@interface ViewController ()
<WKUIDelegate>
@property (nonatomic, strong) WKWebView *webView;
@property (nonatomic, strong) UIToolbar *toolbar;
@property (nonatomic, strong) UIBarButtonItem *buttonForAlert;
@property (nonatomic, strong) UIBarButtonItem *buttonForConfirm;
@property (nonatomic, strong) UIBarButtonItem *buttonForPrompt;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];


    /*
     * Setup WKWebView only for WKUIDelegate
     */
    WKWebViewConfiguration *configuration = [[WKWebViewConfiguration alloc] init];
    _webView = [[WKWebView alloc] initWithFrame:CGRectZero configuration:configuration];
    _webView.UIDelegate = self;
    NSString *urlString = @"https://www.google.com";
    NSURL *url = [NSURL URLWithString:urlString];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [_webView loadRequest:request];


    /*
     * Setup Toolbar
     */
    _buttonForAlert = [[UIBarButtonItem alloc] initWithTitle:@"Alert"
                                                       style:UIBarButtonItemStylePlain
                                                      target:self
                                                      action:@selector(showAlert:)];
    _buttonForConfirm = [[UIBarButtonItem alloc] initWithTitle:@"Confirm"
                                                         style:UIBarButtonItemStylePlain
                                                        target:self
                                                        action:@selector(showConfirm:)];
    _buttonForPrompt = [[UIBarButtonItem alloc] initWithTitle:@"Prompt"
                                                        style:UIBarButtonItemStylePlain
                                                       target:self
                                                       action:@selector(showPrompt:)];
    _buttonForAlert.width   = 80.0;
    _buttonForConfirm.width = 80.0;
    _buttonForPrompt.width  = 80.0;
    _toolbar = [[UIToolbar alloc] initWithFrame:CGRectZero];
    UIBarButtonItem *spacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
                                                                            target:nil
                                                                            action:nil];
    _toolbar.items = @[_buttonForAlert, spacer, _buttonForConfirm, spacer, _buttonForPrompt];

    [self.view addSubview:_webView];
    [self.view addSubview:_toolbar];
    [self setupConstraints];
}

-  ( Void ) ShowAlert: ( UIBarButtonItem  * ) Sender 
{ 
    NSString  * PromptCode  =  Atto "Alert ( 'Alert was pressed');" ; 
    [ _WebView  EvaluateJavaScript : PromptCode  completionHandler : ^ ( Id  Object ,  NSError  * Error )  {  } ]; 
}

- (void)showConfirm:(UIBarButtonItem *)sender
{
    NSString *promptCode = @"var confirmed = confirm('OK?');";
    [_webView evaluateJavaScript:promptCode completionHandler:^(id object, NSError *error) { }];
}

-  ( Void ) ShowPrompt: ( UIBarButtonItem  * ) Sender 
{ 
    NSString  * PromptCode  =  Atto "Var Person = Prompt ( 'Please enter a name', 'default');" ; 
    [ _WebView  EvaluateJavaScript : PromptCode  completionHandler : ^ ( Id  Object ,  NSError  * error )  {  }]; 
}


#pragma mark - WKUIDelegate

- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)())completionHandler
{
    NSString *hostString = webView.URL.host;
    NSString *sender = [NSString stringWithFormat:@"%@", hostString];

    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:message message:sender preferredStyle:UIAlertControllerStyleAlert];

    [alertController addAction:[UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
        completionHandler();
    }]];
    [self presentViewController:alertController animated:YES completion:^{}];
}

- (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString *))completionHandler
{
    NSString *hostString = webView.URL.host;
    NSString *sender = [NSString stringWithFormat:@"%@", hostString];

    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:prompt message:sender preferredStyle:UIAlertControllerStyleAlert];
    [alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {
        //textField.placeholder = defaultText;
        textField.text = defaultText;
    }];
    [alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        NSString *input = ((UITextField *)alertController.textFields.firstObject).text;
        completionHandler(input);
    }]];
    [alertController addAction:[UIAlertAction actionWithTitle:@"cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
        completionHandler(nil);
    }]];
    [self presentViewController:alertController animated:YES completion:^{}];
}

- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL))completionHandler
{
    NSString *hostString = webView.URL.host;
    NSString *sender = [NSString stringWithFormat:@"%@", hostString];

    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:message message:sender preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        completionHandler(YES);
    }]];
    [alertController addAction:[UIAlertAction actionWithTitle:@"cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
        completionHandler(NO);
    }]];
    [self presentViewController:alertController animated:YES completion:^{}];
}


#pragma mark - Constraints

- (void)setupConstraints
{
    _webView.translatesAutoresizingMaskIntoConstraints = NO;
    [_webView.superview addConstraints:[NSLayoutConstraint
                                        constraintsWithVisualFormat:@"V:|-20.0-[view]-44.0-|"
                                        options:NSLayoutFormatDirectionLeadingToTrailing
                                        metrics:nil
                                        views:@{@"view":_webView}]];
    [_webView.superview addConstraints:[NSLayoutConstraint
                                        constraintsWithVisualFormat:@"H:|-0-[view]-0-|"
                                        options:NSLayoutFormatDirectionLeadingToTrailing
                                        metrics:nil
                                        views:@{@"view":_webView}]];

    _toolbar.translatesAutoresizingMaskIntoConstraints = NO;
    [_toolbar.superview addConstraints:[NSLayoutConstraint
                                        constraintsWithVisualFormat:@"V:[view]-0-|"
                                        options:NSLayoutFormatDirectionLeadingToTrailing
                                        metrics:nil
                                        views:@{@"view":_toolbar}]];
    [_toolbar.superview addConstraints:[NSLayoutConstraint
                                        constraintsWithVisualFormat:@"H:|-0-[view]-0-|"
                                        options:NSLayoutFormatDirectionLeadingToTrailing
                                        metrics:nil
                                        views:@{@"view":_toolbar}]];
    [_toolbar.superview addConstraint:[NSLayoutConstraint constraintWithItem:_toolbar
                                                               attribute:NSLayoutAttributeHeight
                                                               relatedBy:NSLayoutRelationEqual
                                                                  toItem:nil
                                                               attribute:0
                                                              multiplier:1.0
                                                                constant:44.0]];

}

@end