According to post in Developer News And Updates on December 23, 2019, UIWebView class was deprecated and apps using it will be rejected. I wrote this change in post below.
There are 3 classes to embed the web browser into the iOS app. UIWebView class WKWebView class SFSafariViewCo[…]
We should use WKWebView or SFSafariViewController instead of UIWebView. This post says how to replace UIWebView with WKWebView.
Loading Pages
Load from URL
This code load the web page from URL with UIWebView.
// Swift
// with UIWebView
func load(url: URL) {
let request = URLRequest(url: url)
uiWebView.loadRequest(request)
}// Objective-C
// with UIWebView
- (void)loadWithURL:(NSURL *)url {
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[self.uiWebView loadRequest:request];
}The code to load from URL with WKWebView is looking like same.
// Swift
// with WKWebView
func load(url: URL) {
let request = URLRequest(url: url)
wkWebView.load(request)
}// Objective-C
// with WKWebView
#import <WebKit/WebKit.h>
- (void)loadWithURL:(NSURL *)url {
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[self.wkWebView loadRequest:request];
}Load from the local HTML
This code load the local HTML data with UIWebView. The HTML is a string.
// Swift
uiWebView.loadHTMLString(html, baseURL: baseURL)// Objective-C
[self.uiWebView loadHTMLString:html
baseURL:baseURL];The code is using WKWebView is below. It is very similar with above.
// Swift
_ = wkWebView.loadHTMLString(html, baseURL: baseURL)// Objective-C
[self.wkWebView loadHTMLString:html
baseURL:baseURL]Execute JavaScript
This code executes the JavaScript with UIWebView.
// Swift
let result = uiWebView.stringByEvaluatingJavaScript(from: script)// Objective-C
id result = [self.uiWebView stringByEvaluatingJavaScriptFromString:script];The code is using WKWebView is below.
// Swift
wkWebView.evaluateJavaScript(script) { (result, error) in
}// Objective-C版
NSString *script = @"document.title";
[self.wkWebView evaluateJavaScript:script completionHandler:^(id _Nullable result, NSError * _Nullable error) {
}];UIWebView executes the JavaScript synchronously, the method returns after execution was completed.
WKWebView executes the JavaScript asynchronously, the method return immediately. The execution is completed, the completion block will be performed. You can execute other JavaScript in the completion block.
Perform the operation before and after loading pages
If you want do anything just before or after the page is loading, you need to implement the class adopts to the UIWebViewDelegate protocol.
// Swift
import UIKit
class ViewController: UIViewController, UIWebViewDelegate {
@IBOutlet var uiWebView: UIWebView!
override func viewDidLoad() {
super.viewDidLoad()
uiWebView.delegate = self
load(url: URL(string: "http://www.example.com")!)
}
func load(url: URL) {
let request = URLRequest(url: url)
uiWebView.loadRequest(request)
}
/// Perform just before loading page
func webViewDidStartLoad(_ webView: UIWebView) {
print("Start Loading Page")
}
/// Perform just after loading page
func webViewDidFinishLoad(_ webView: UIWebView) {
print("Finish Loading Page")
}
/// Perform when any errors are encounted
func webView(_ webView: UIWebView, didFailLoadWithError error: Error) {
print("Failed Loading Page: \(error)")
}
}// Objective-C
#import "ViewController.h"
@interface ViewController () <UIWebViewDelegate>
@end
@implementation ViewController
@synthesize uiWebView = _uiWebView;
- (void)viewDidLoad {
[super viewDidLoad];
self.uiWebView.delegate = self;
[self loadWithURL:[NSURL URLWithString:@"https://www.example.com"]];
}
- (void)loadWithURL:(NSURL *)url {
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[self.uiWebView loadRequest:request];
}
/// Perform just before loading page
- (void)webViewDidStartLoad:(UIWebView *)webView {
NSLog(@"Start Loading Page");
}
/// Perform just after loading page
- (void)webViewDidFinishLoad:(UIWebView *)webView {
NSLog(@"Finish Loading Page");
}
/// Perform when any errors are encountered
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error {
NSLog(@"Failed Loading Page: %@", error.localizedDescription);
}
@endWith WKWebView, you need to implement the class adopts WKNavigationDelegate protocol.
WKNavigationDelegate protocol has more methods variations. For example, it is divided into 2 methods that is called just before loading page, preparing and contents. If the specified URL is not reachable, webView(_:didStartProvisisionalNavigation:) method will be called but webView(_:didCommit:) will not.
// Swift
import UIKit
import WebKit
class ViewController: UIViewController, WKNavigationDelegate {
@IBOutlet var wkWebView: WKWebView!
override func viewDidLoad() {
super.viewDidLoad()
wkWebView.navigationDelegate = self
load(url: URL(string: "https://www.example.com/")!)
}
func load(url: URL) {
let request = URLRequest(url: url)
wkWebView.load(request)
}
/// Perform just before loading page
func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
print("Start Provisional Navigation")
}
/// Perform just before loading contents of page
func webView(_ webView: WKWebView, didCommit navigation: WKNavigation!) {
print("Did Commit")
}
/// Perform just after loading page
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
print("Did Finish")
}
/// Perform when any errors are encountered
func webView(_ webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: Error) {
print("Did Fail Provisional Navigation")
}
}
// Objective-C
#import "ViewController.h"
@interface ViewController () <WKNavigationDelegate>
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.wkWebView.navigationDelegate = self;
[self loadWithURL:[NSURL URLWithString:@"https://www.example.com"]];
}
- (void)loadWithURL:(NSURL *)url {
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[self.wkWebView loadRequest:request];
}
/// Perform just before loading page
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {
NSLog(@"Start Provisional Navigation");
}
/// Perform just before loading contents of page - (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation { NSLog(@"Did Commit"); } /// Perform just after loading page - (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation { NSLog(@"Did Finish"); } /// Perform when any errors are encountered - (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation withError:(NSError *)error { NSLog(@"Did Fail Provisional Navigation"); } @endConclusion
WKWebView has more rich functionality and more delegate methods than UIWebView. It seems that WKWebView is more flexible.
Related Posts
WKWebViewに関連するその他の記事です。
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- A professional developer specializing in macOS Apps, iOS Apps, SDKs and middleware development.
- Representative of RK Kaihatsu. I am a professional developer specializing in macOS Apps, iOS Apps, SDKs and middleware development. I often use ObjC, Swift and C++. Based on development experience, I provide e-learning contents, technical books and technical guidance. I am also a technical seminar instructor, in-house training instructor, and administrative / local goverment staff training instructor.