在开发过程中，iOS 中实现加载 web 页面主要有两种控件，UIWebView 和 WKWebview，两种控件对应具体的实现方法不同。WKWebView是苹果公司在iOS8系统推出的，这里主要概述WebKit中更新的WKWebView控件的新特性与使用方法，以及小编在开发过程中踩的坑。

@property (nullable, nonatomic, readonly, copy) NSString *title;@property (nullable, nonatomic, readonly, copy) NSURL *URL;@property (nonatomic, readonly, getter=isLoading) BOOL loading;
//加载进度
@property (nonatomic, readonly) double estimatedProgress;

- (nullable WKNavigation *)loadRequest:(NSURLRequest *)request;- (nullable WKNavigation *)loadFileURL:(NSURL *)URL allowingReadAccessToURL:(NSURL *)readAccessURL API_AVAILABLE(macosx(10.11), ios(9.0));- (nullable WKNavigation *)loadHTMLString:(NSString *)string baseURL:(nullable NSURL *)baseURL;- (nullable WKNavigation *)loadData:(NSData *)data MIMEType:(NSString *)MIMEType characterEncodingName:(NSString *)characterEncodingName baseURL:(NSURL *)baseURL API_AVAILABLE(macosx(10.11), ios(9.0));

#pragma mark - WKNavigationDelegate
/* 页面开始加载 */
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation{NSLog(@"页面开始加载");
}
/* 开始返回内容 */
- (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation{NSLog(@"开始返回内容");
}
/* 页面加载完成 */
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation{NSLog(@"页面加载完成");
}
/* 页面加载失败 */
- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation{NSLog(@"页面加载失败");
}
/* 在发送请求之前，决定是否跳转 */
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler{//允许跳转decisionHandler(WKNavigationActionPolicyAllow);//不允许跳转//decisionHandler(WKNavigationActionPolicyCancel);
}
/* 在收到响应后，决定是否跳转 */
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{NSLog(@"%@",navigationResponse.response.URL.absoluteString);//允许跳转decisionHandler(WKNavigationResponsePolicyAllow);//不允许跳转//decisionHandler(WKNavigationResponsePolicyCancel);
}

<WKUIDelegate, WKNavigationDelegate>

#pragma mark - 创建webView
- (void)createWebView{WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];config.selectionGranularity = WKSelectionGranularityDynamic;config.allowsInlineMediaPlayback = YES;WKPreferences *preferences = [WKPreferences new];//是否支持JavaScriptpreferences.javaScriptEnabled = YES;//不通过用户交互，是否可以打开窗口preferences.javaScriptCanOpenWindowsAutomatically = YES;config.preferences = preferences;self.webView = [[WKWebView alloc] initWithFrame:self.view.bounds];[self.view addSubview:self.webView];/* 加载服务器url的方法*/NSString *url = @"https://www.baidu.com";NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:url]];[self.webView loadRequest:request];self.webView.navigationDelegate = self;self.webView.UIDelegate = self;}

- (void)createProgressView{self.progressView = [[UIProgressView alloc] initWithFrame:CGRectMake(0, 88, SCREEN_WIDTH, 2)];self.progressView.progressViewStyle = UIProgressViewStyleDefault;self.progressView.tintColor = [UIColor blueColor];self.progressView.trackTintColor = [UIColor greenColor];[self.view addSubview:self.progressView];
}

[self.webView addObserver:self forKeyPath:@"estimatedProgress" options:NSKeyValueObservingOptionNew context:nil];
[self.webView addObserver:self forKeyPath:@"title" options:NSKeyValueObservingOptionNew context:NULL];

#pragma mark - KVO回馈
-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{if ([keyPath isEqualToString:@"estimatedProgress"]) {double progress = _webView.estimatedProgress;self.progressView.alpha = 1.0f;[self.progressView setProgress:progress animated:YES];if(progress >= 1){[UIView animateWithDuration:0.25 delay:0.25 options:UIViewAnimationOptionCurveEaseOut animations:^{self.progressView.alpha = 0.0f;} completion:^(BOOL finished) {[self.progressView setProgress:0.0f animated:NO];}];}if ([change[@"new"] floatValue] <[change[@"old"] floatValue]) {return;}if ([change[@"new"]floatValue] == 1.0) {dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{});}}else if ([keyPath isEqualToString:@"title"]){self.title = change[@"new"];}
}