iOS中UIWebView网页加载组件的基础及使用技巧实例

基本用法示例

- (void)viewDidLoad{ [super viewDidLoad]; // Do any additional setup after loading the view. UIWebView * webView = [[UIWebView alloc]initWithFrame:CGRectMake(0, 20, ScreenWidth, ScreenHeight-20)]; // 自动队页面进行缩放以适应屏幕 webView.scalesPageToFit = YES; webView.userInteractionEnabled = YES; webView.opaque = YES; [self.view addSubview:webView]; NSURL * url = [NSURL URLWithString:@"http://"]; NSURLRequest * request = [NSURLRequest requestWithURL:url]; [webView loadRequest:request];// NSString * myHT = @"优酷";// [webView loadHTMLString:myHT baseURL:url]; webView.delegate = self; //移除滚动后的外边阴影 UIScrollView *scrollView = webView.scrollView; for (int i = 0; i < scrollView.subviews.count ; i++) { UIView *view = [scrollView.subviews objectAtIndex:i]; if ([view isKindOfClass:[UIImageView class]]) { view.hidden = YES ; } }}#pragma mark - UIWebViewDelegate- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{ /** * typedef NS_ENUM(NSInteger, UIWebViewNavigationType) { * UIWebViewNavigationTypeLinkClicked, * UIWebViewNavigationTypeFormSubmitted, * UIWebViewNavigationTypeBackForward, * UIWebViewNavigationTypeReload, * UIWebViewNavigationTypeFormResubmitted, * UIWebViewNavigationTypeOther }; */ NSLOG_FUNCTION; return YES;}// 开始加载- (void)webViewDidStartLoad:(UIWebView *)webView{ NSLOG_FUNCTION;}// 完成加载- (void)webViewDidFinishLoad:(UIWebView *)webView{ NSLOG_FUNCTION;}// 加载失败,弹出错误提示- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error{ UIAlertView *alterview = [[UIAlertView alloc] initWithTitle:@"" message:[error localizedDescription] delegate:nil cancelButtonTitle:nil otherButtonTitles:@"OK", nil]; [alterview show]; [alterview release]; NSLOG_FUNCTION;}

以下是关于它的一些使用技巧：

1.让网页适应手机屏幕宽度

如果用UIWebView显示一些pc站的网页，会发现网页会超出屏幕，显得很不好看，这时可以在webViewDidFinishLoad这个代理里面通过js添加一个meta：

- (void)webViewDidFinishLoad:(UIWebView *)webView{ NSString *meta = [NSString stringWithFormat:@"document.getElementsByName(\"viewport\")[0].content = \"width=%f, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no\"", IPHONE_WIDTH]; [webView stringByEvaluatingJavaScriptFromString:meta];}

注意：使用这个方法时要把UIWebView的scalesPageToFit设成NO

webView.scalesPageToFit = NO;

2.为网页中的图片添加点击事件，当点击图片时放大查看

思路是给每一个img标签添加onclick事件，在事件中把img的src属性封装成一个特殊的url，然后进行拦截

如果是通过loadHTMLString去加载网页的话，可以执行下面一句进行替换：

复制代码代码如下:

html = [html stringByReplacingOccurrencesOfString:@"<img " withString:@"<img onclick=\"window.location.href=('http://src.'+this.src);\" "];

如果是通过loadRequest，那就要再webViewDidFinishLoad中执行以下JS：

NSString *js = @"var imgs = document.getElementsByTagName(\"img\");" "for(var i=0;i<imgs.length;i++){" " var img = imgs[i];" " img.onclick=function(){window.location.href=('http://src.'+this.src);}" "}"; [webView stringByEvaluatingJavaScriptFromString:js];

然后通过webview的代理方法去拦截，拿到图片的url，之后就可以做各种处理了

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{ NSString *url = request.URL.absoluteString; if ([url hasPrefix:@"http://src."]) { url = [url stringByReplacingOccurrencesOfString:@"http://src." withString:@""]; // Do something.. return NO; } return YES;}

3.为UIWebView添加一个跟随网页滚动的页头

UIWebView里包含一个scrollview，可以向scrollview里添加一个页头以达到跟随网页滚动的效果

CGFloat headerHeight = 36.0f;// 注意：y坐标必须是负数，IPHONE_WIDTH是屏幕宽度UIView *headerView = [[UIView alloc] initWithFrame:CGRectMake(0, -headerHeight, IPHONE_WIDTH, headerHeight)];[_webView.scrollView addSubview:_headerView];// 修改webView的scrollView的contentInset，让顶部留出一点空间UIEdgeInsets edgeInset = _webView.scrollView.contentInset;_webView.scrollView.contentInset = UIEdgeInsetsMake(headerView.frameHeight, edgeInset.left, edgeInset.bottom, edgeInset.right);

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