发布于 2016-04-25 10:54:48 | 548 次阅读 | 评论: 0 | 来源: 网友投递
Swift编程语言
SWIFT,苹果于2014年WWDC(苹果开发者大会)发布的新开发语言,可与Objective-C*共同运行于Mac OS和iOS平台,用于搭建基于苹果平台的应用程序。
自从iOS8开始,Apple引入了WKWebView欲代替UIWebView。相比而言,WKWebView消耗内从更少,功能也更加强大。让我们来看看WKWebView怎么使用吧!
0.初始化
(1)首先需要引入WebKit库
#import <WebKit/WebKit.h>
// 默认初始化
- (instancetype)initWithFrame:(CGRect)frame;
// 根据对webview的相关配置,进行初始化
- (instancetype)initWithFrame:(CGRect)frame configuration:(WKWebViewConfiguration *)configuration NS_DESIGNATED_INITIALIZER;
WKWebView *webView = [[WKWebView alloc] initWithFrame:self.view.bounds];
[webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]];
[self.view addSubview:webView];
1. WKWebView的代理方法
(1) WKNavigationDelegate
该代理提供的方法,可以用来追踪加载过程(页面开始加载、加载完成、加载失败)、决定是否执行跳转。
// 页面开始加载时调用
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation;
// 当内容开始返回时调用
- (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation;
// 页面加载完成之后调用
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation;
// 页面加载失败时调用
- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation;
// 接收到服务器跳转请求之后调用
- (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation;
// 在收到响应后,决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler;
// 在发送请求之前,决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler;
// 创建一个新的WebView
- (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures;
/**
* web界面中有弹出警告框时调用
*
* @param webView 实现该代理的webview
* @param message 警告框中的内容
* @param frame 主窗口
* @param completionHandler 警告框消失调用
*/
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(void (^)())completionHandler;
// 从web界面中接收到一个脚本时调用
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message;
2.修改Info.plist
注意从iOS9开始,凡是涉及到网络操作的,都要在Info.plist中加入:
3.加载网页
先要在ViewController 导入WebKit:
import WebKit
var webview = WKWebView()
override func viewDidLoad() {
super.viewDidLoad()
//创建wkwebview
let webview = WKWebView(frame: CGRectMake(0, 0, self.view.frame.width, self.view.frame.height))
//创建网址
let url = NSURL(string: "http://www.jianshu.com/users/040395b7230c/latest_articles")
//创建请求
let request = NSURLRequest(URL: url!)
//加载请求
webview.loadRequest(request)
//添加wkwebview
self.view.addSubview(webview)
}
4.获取网页标题
为了显示标题,首先给ViewController嵌入一个NavigationController。有了导航栏后,我们要调整一下webview的y轴位置,防止导航栏遮住网页上面部分,在viewDidLoad()里写上:
//获取导航栏高度
let navHeight = self.navigationController?.navigationBar.frame.height
//获取状态栏高度
let statusHeight = UIApplication.sharedApplication().statusBarFrame.height
webview = WKWebView(frame: CGRectMake(0, statusHeight+navHeight!,self.view.frame.width, self.view.frame.height))
self.webview.navigationDelegate = self
func webView(webView: WKWebView, didFinishNavigation navigation: WKNavigation!) {
self.navigationItem.title = self.webview.title
}
5.前进和后退
首先我们要在navgationBar上添加前进和后退按钮:
var btnBack = UIBarButtonItem()
var btnForward = UIBarButtonItem()
func setNavBar() {
btnBack = UIBarButtonItem(title: "后退", style: UIBarButtonItemStyle.Plain, target: self, action: "toBack")
btnForward = UIBarButtonItem(title: "前进", style: UIBarButtonItemStyle.Plain, target: self, action: "toForward")
self.navigationItem.leftBarButtonItem = btnBack
self.navigationItem.rightBarButtonItem = btnForward
}
func toBack() {
if self.webview.canGoBack {
self.webview.goBack()
}
}
func toForward() {
if self.webview.canGoForward {
self.webview.goForward()
}
}
setNavBar()
6.修改网页配置
现在,一个看似很简单的浏览器完成了,但如果我们把网址换成:
http://csol2.tiancity.com/homepage/article/Class_1166_Time_1.html
即在viewDidLoad()里修改:
let url = NSURL(string: "http://csol2.tiancity.com/homepage/article/Class_1166_Time_1.html")
self.webview.UIDelegate = self
func webView(webView: WKWebView, createWebViewWithConfiguration configuration: WKWebViewConfiguration, forNavigationAction navigationAction: WKNavigationAction, windowFeatures: WKWindowFeatures) -> WKWebView? {
//如果目标主视图不为空,则允许导航
if !(navigationAction.targetFrame?.mainFrame != nil) {
self.webview.loadRequest(navigationAction.request)
}
return nil
}
7.处理js的提示框
现在把网址修改为
http://evt.tiancity.com/csol2/1565/home/index.php
即在viewDidLoad()里修改:
let url = NSURL(string: "http://evt.tiancity.com/csol2/1565/home/index.php")
func webView(webView: WKWebView, runJavaScriptAlertPanelWithMessage message: String, initiatedByFrame frame: WKFrameInfo, completionHandler: () -> Void) {
let alert = UIAlertController(title: nil, message: message, preferredStyle: .Alert)
alert.addAction(UIAlertAction(title: "Ok", style: .Default, handler: { (_) -> Void in
completionHandler()
}))
self.presentViewController(alert, animated: true, completion: nil)
}
8.添加进度条
我们知道UIWebView是无法获取网页加载的进度的,于是也就无法创建进度条了,当然我们可以以某种算法模拟网页加载,自己设置进度条的值。而WKWebView却提供了获取网页加载进度的方法,支持KVO,也就是estimatedProgress。另外还有loading是否正在加载和title页面标题。
我们得创建一个进度条:
var progBar = UIProgressView()
//以下代码添加到viewDidLoad()
progBar = UIProgressView(frame: CGRectMake(0, 0, self.view.frame.width, 30))
progBar.progress = 0.0
progBar.tintColor = UIColor.redColor()
self.webview.addSubview(progBar)
self.webview.addObserver(self, forKeyPath: "estimatedProgress", options: NSKeyValueObservingOptions.New, context: nil)
override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
if keyPath == "estimatedProgress" {
self.progBar.alpha = 1.0
progBar.setProgress(Float(webview.estimatedProgress), animated: true)
//进度条的值最大为1.0
if(self.webview.estimatedProgress >= 1.0) {
UIView.animateWithDuration(0.3, delay: 0.1, options: UIViewAnimationOptions.CurveEaseInOut, animations: { () -> Void in
self.progBar.alpha = 0.0
}, completion: { (finished:Bool) -> Void in
self.progBar.progress = 0
})
}
}
}
还有一点别忘了,对于KVO模式,有add一定要remove,否则会崩溃。我们可以在视图消失的时候添加remove:
override func viewWillDisappear(animated: Bool) {
webview.removeObserver(self, forKeyPath: "estimatedProgress")
}
9.最终效果图
10.总结
WKWebView的简单使用就介绍到这里了!大家有兴趣可以为其添加更多功能!如果喜欢本文的话别忘了点击喜欢哦!
后记
既然说WKWebView相比UIWebView消耗的内存更少,那么我们就来实际对比一下,我们让它们加载同一个网站,结果如图
(左为UIWebView,右为WKWebView):