iOS UIWebView与WKWebView使用详解

一、整体介绍

UIWebView自iOS2就有，WKWebView从iOS8才有，毫无疑问WKWebView将逐步取代笨重的UIWebView。通过简单的测试即可发现UIWebView占用过多内存，且内存峰值更是夸张。WKWebView网页加载速度也有提升，但是并不像内存那样提升那么多。下面列举一些其它的优势： 

• 更多的支持HTML5的特性
• 官方宣称的高达60fps的滚动刷新率以及内置手势
• Safari相同的JavaScript引擎
• 将UIWebViewDelegate与UIWebView拆分成了14类与3个协议(官方文档说明)
• 另外用的比较多的，增加加载进度属性：estimatedProgress

二、UIWebView使用说明

1 举例：简单的使用

UIWebView使用非常简单，可以分为三步，也是最简单的用法，显示网页

- (void)simpleExampleTest {
    // 1.创建webview，并设置大小，"20"为状态栏高度
    UIWebView *webView = [[UIWebView alloc] initWithFrame:CGRectMake(0, 20, self.view.frame.size.width, self.view.frame.size.height - 20)];
    // 2.创建请求
    NSMutableURLRequest *request =[NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.cnblogs.com/mddblog/"]];
    // 3.加载网页
    [webView loadRequest:request];
    
    // 最后将webView添加到界面
    [self.view addSubview:webView];
}

2 一些实用函数

• 加载函数。

- (void)loadRequest:(NSURLRequest *)request;
- (void)loadHTMLString:(NSString *)string baseURL:(nullable NSURL *)baseURL;
- (void)loadData:(NSData *)data MIMEType:(NSString *)MIMEType textEncodingName:(NSString *)textEncodingName baseURL:(NSURL *)baseURL;

UIWebView不仅可以加载HTML页面，还支持pdf、word、txt、各种图片等等的显示。下面以加载mac桌面上的png图片：/Users/coohua/Desktop/bigIcon.png为例 

// 1.获取url
NSURL *url = [NSURL fileURLWithPath:@"/Users/coohua/Desktop/bigIcon.png"];
// 2.创建请求
NSURLRequest *request=[NSURLRequest requestWithURL:url];
// 3.加载请求
[self.webView loadRequest:request];

• 网页导航刷新有关函数

// 刷新
- (void)reload;
// 停止加载
- (void)stopLoading;
// 后退函数
- (void)goBack;
// 前进函数
- (void)goForward;
// 是否可以后退
@property (nonatomic, readonly, getter=canGoBack) BOOL canGoBack;
// 是否可以向前
@property (nonatomic, readonly, getter=canGoForward) BOOL canGoForward;
// 是否正在加载
@property (nonatomic, readonly, getter=isLoading) BOOL loading;

3 代理协议使用：UIWebViewDelegate

一共有四个方法

/// 是否允许加载网页，也可获取js要打开的url，通过截取此url可与js交互
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
    
    NSString *urlString = [[request URL] absoluteString];
    urlString = [urlString stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    
    NSArray *urlComps = [urlString componentsSeparatedByString:@"://"];
    NSLog(@"urlString=%@---urlComps=%@",urlString,urlComps);
    return YES;
}
/// 开始加载网页
- (void)webViewDidStartLoad:(UIWebView *)webView {
    NSURLRequest *request = webView.request;
    NSLog(@"webViewDidStartLoad-url=%@--%@",[request URL],[request HTTPBody]);
}
/// 网页加载完成
- (void)webViewDidFinishLoad:(UIWebView *)webView {
    NSURLRequest *request = webView.request;
    NSURL *url = [request URL];
    if ([url.path isEqualToString:@"/normal.html"]) {
        NSLog(@"isEqualToString");
    }
    NSLog(@"webViewDidFinishLoad-url=%@--%@",[request URL],[request HTTPBody]);
    NSLog(@"%@",[self.webView stringByEvaluatingJavaScriptFromString:@"document.title"]);
}
/// 网页加载错误
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error {
    NSURLRequest *request = webView.request;
    NSLog(@"didFailLoadWithError-url=%@--%@",[request URL],[request HTTPBody]);
    
}

4 与js交互

主要有两方面：js执行OC代码、oc调取写好的js代码 

• js执行OC代码：js是不能执行oc代码的，但是可以变相的执行，js可以将要执行的操作封装到网络请求里面，然后oc拦截这个请求，获取url里面的字符串解析即可，这里用到代理协议的- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType函数。
• oc调取写好的js代码：这里用到UIwebview的一个方法。示例代码一个是网页定位，一个是获取网页title：

// 实现自动定位js代码, htmlLocationID为定位的位置(由js开发人员给出)，实现自动定位代码，应该在网页加载完成之后再调用
NSString *javascriptStr = [NSString stringWithFormat:@"window.location.href = '#%@'",htmlLocationID];
// webview执行代码
[self.webView stringByEvaluatingJavaScriptFromString:javascriptStr];

// 获取网页的title
NSString *title = [self.webView stringByEvaluatingJavaScriptFromString:@"document.title"];

• 与js交互的实例

很多时候，我们要对网页做一些编辑，比如加载一个网页后，个别原因，我们不想显示新闻的来源，如下图的新闻来源“新华网”，网页的链接如下：http://op.inews.qq.com/mcms/h5/default/detail?id=NEW2016103101306200&refer=100000050(可能已经失效)

那我们就可以使用js代码将这个标签去掉，且只留下时间。js代码的编写，根据火狐浏览器查看它的标签名称，然后做处理，如上图，具体代码如下：

- (void)deleteNewsSource {
    // 1.去掉页面标题
    NSMutableString *str = [NSMutableString string];
    // 去掉导航页，如果想把“腾讯新闻”导航栏一并去掉，就打开注释
//    [str appendString:@"document.getElementsByClassName('g-header')[0].style.display = 'none';"];
    // 来源
    [str appendString:@"if(document.getElementsByClassName('g-wrapper-author')[0].innerHTML.indexOf(' ') == -1){document.getElementsByClassName('g-wrapper-author')[0].innerHTML = document.getElementsByClassName('g-wrapper-author')[0].innerHTML}else{document.getElementsByClassName('g-wrapper-author')[0].innerHTML = document.getElementsByClassName('g-wrapper-author')[0].innerHTML.split(' ')[1];}"];
    // 执行js代码
    [_webView stringByEvaluatingJavaScriptFromString:str];
}

代码执行的时机，一般情况下是等待网页加载完成- (void)webViewDidFinishLoad:(UIWebView *)webView里面执行，比较合理，但是有延迟，我们会发现刚开始有来源，然后突然又没有了，即js代码执行有延迟。

这样的话，我们可以在- (void)webViewDidStartLoad:(UIWebView *)webView网页开始加载里面开启一个定时器，比如定时0.2秒（根据需要自己设定），在定时器里面不停的调用- (void)deleteNewsSource方法即可解决。然后在- (void)webViewDidFinishLoad:(UIWebView *)webView里面关掉定时器。另外定时器容易引起循环引用，一定要注意释放。比如可以在viewDidDisappear方法里释放定时器。。。

- (void)webViewDidStartLoad:(UIWebView *)webView {
    // 1.去掉页面来源标签，时间根据需要自己设置，定时器在这里开启具有一定危险性
    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.2 target:self selector:@selector(deleteNewsSource) userInfo:nil repeats:YES];
    [[NSRunLoop mainRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
    self.timer = timer;
}

三、WKWebView使用说明

1 简单使用

与UIWebview一样，仅需三步:

- (void)simpleExampleTest {
    // 1.创建webview，并设置大小，"20"为状态栏高度
    WKWebView *webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 20, self.view.frame.size.width, self.view.frame.size.height - 20)];
    // 2.创建请求
    NSMutableURLRequest *request =[NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.cnblogs.com/mddblog/"]];
    // 3.加载网页
    [webView loadRequest:request];
    
    // 最后将webView添加到界面
    [self.view addSubview:webView];
}

2 一些实用函数

• 加载网页函数
  相比UIWebview，WKWebView也支持各种文件格式，并新增了loadFileURL函数，顾名思义加载本地文件，不要用loadRequest来加载本地HTML，另外，加载网页显示属于UI，所以应在主线程里面执行加载网页函数，不过即使在其它线程执行了加载网页函数，也没关系，苹果已做了处理，保证UI在主线程更新。

/// 模拟器调试加载mac本地文件
- (void)loadLocalFile {
    // 1.创建webview，并设置大小，"20"为状态栏高度
    WKWebView *webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 20, self.view.frame.size.width, self.view.frame.size.height - 20)];
    // 2.创建url  userName：电脑用户名
    NSURL *url = [NSURL fileURLWithPath:@"/Users/userName/Desktop/bigIcon.png"];
    // 3.加载文件
    [webView loadFileURL:url allowingReadAccessToURL:url];
    // 最后将webView添加到界面
    [self.view addSubview:webView];
}

/// 其它三个加载函数
- (WKNavigation *)loadRequest:(NSURLRequest *)request;
- (WKNavigation *)loadHTMLString:(NSString *)string baseURL:(nullable NSURL *)baseURL;
- (WKNavigation *)loadData:(NSData *)data MIMEType:(NSString *)MIMEType characterEncodingName:(NSString *)characterEncodingName baseURL:(NSURL *)baseURL;

• 网页导航刷新相关函数
  和UIWebview几乎一样，不同的是有返回值，WKNavigation(已更新)，另外增加了函数reloadFromOrigin和goToBackForwardListItem。
  
  • reloadFromOrigin会比较网络数据是否有变化，没有变化则使用缓存，否则从新请求。
  • goToBackForwardListItem：比向前向后更强大，可以跳转到某个指定历史页面

@property (nonatomic, readonly) BOOL canGoBack;
@property (nonatomic, readonly) BOOL canGoForward;
- (WKNavigation *)goBack;
- (WKNavigation *)goForward;
- (WKNavigation *)reload;
- (WKNavigation *)reloadFromOrigin; // 增加的函数
- (WKNavigation *)goToBackForwardListItem:(WKBackForwardListItem *)item; // 增加的函数
- (void)stopLoading;

• 一些常用属性
  • allowsBackForwardNavigationGestures：BOOL类型，是否允许左右划手势导航，默认不允许
  • estimatedProgress：加载进度，取值范围0~1
  • title：页面title
  • .scrollView.scrollEnabled：是否允许上下滚动，默认允许
  • backForwardList：WKBackForwardList类型，访问历史列表，可以通过前进后退按钮访问，或者通过goToBackForwardListItem函数跳到指定页面

• 执行js代码

/// jsStr为要执行的js代码，字符串形式
[webView evaluateJavaScript:jsStr completionHandler:^(id item, NSError * _Nullable error) {
        // 执行结果回调
}];

3 代理协议使用

一共有三个代理协议： 

• WKNavigationDelegate：最常用，和UIWebViewDelegate功能类似，追踪加载过程，有是否允许加载、开始加载、加载完成、加载失败。下面会对函数做简单的说明，并用数字标出调用的先后次序：1-2-3-4-5

三个是否允许加载函数：

/// 接收到服务器跳转请求之后调用 (服务器端redirect)，不一定调用
- (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation; 
/// 3 在收到服务器的响应头，根据response相关信息，决定是否跳转。decisionHandler必须调用，来决定是否跳转，参数WKNavigationActionPolicyCancel取消跳转，WKNavigationActionPolicyAllow允许跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler;
/// 1 在发送请求之前，决定是否跳转 
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler; 

追踪加载过程函数:

/// 2 页面开始加载
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation;
/// 4 开始获取到网页内容时返回
- (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation;
/// 5 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;

• WKScriptMessageHandler：必须实现的函数，是APP与js交互，提供从网页中收消息的回调方法，即js可以调用app的方法

当然需要对webview做一些特殊处理，创建的时候调用initWithFrame:configuration:做一些配置,configuration为WKWebViewConfiguration类型，具体不再详述，代理方法如下：

/// message: 收到的脚本信息.
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message;

当然，app也可以执行js代码，如下：

/// jsStr为要执行的js代码，字符串形式
[webView evaluateJavaScript:jsStr completionHandler:^(id item, NSError * _Nullable error) {
        // 执行结果回调
}];

• WKUIDelegate：UI界面相关，原生控件支持，三种提示框：输入、确认、警告。首先将web提示框拦截然后再做处理。

/// 创建一个新的WebView
- (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures;
/// 输入框
- (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(nullable NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString * __nullable result))completionHandler;
/// 确认框
- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL result))completionHandler;
/// 警告框
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler;

四、示例代码

• 代码可以实现一般网络显示，加载本地文件(pdf、word、txt、图片等等)
• 搜索框搜索界面，搜索框输入file://则加载本地文件，http://则加载网络内容，如果两者都不是则搜索输入的关键字。
• 下部网络导航，后退、前进、刷新、用Safari打开链接四个按钮

/// 控件高度
#define kSearchBarH  44
#define kBottomViewH 44

/// 屏幕大小尺寸
#define kScreenWidth  [UIScreen mainScreen].bounds.size.width
#define kScreenHeight [UIScreen mainScreen].bounds.size.height

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


@interface ViewController () <UISearchBarDelegate, WKNavigationDelegate>

@property (nonatomic, strong) UISearchBar *searchBar;
/// 网页控制导航栏
@property (weak, nonatomic) UIView *bottomView;

@property (nonatomic, strong) WKWebView *wkWebView;

@property (weak, nonatomic) UIButton *backBtn;
@property (weak, nonatomic) UIButton *forwardBtn;
@property (weak, nonatomic) UIButton *reloadBtn;
@property (weak, nonatomic) UIButton *browserBtn;

@property (weak, nonatomic) NSString *baseURLString;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
//    [self simpleExampleTest];
    
    [self addSubViews];
    [self refreshBottomButtonState];
    
    [self.wkWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.cnblogs.com/mddblog/"]]];
    
}
- (void)simpleExampleTest {
    // 1.创建webview，并设置大小，"20"为状态栏高度
    WKWebView *webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 20, self.view.frame.size.width, self.view.frame.size.height - 20)];
    // 2.创建请求
    NSMutableURLRequest *request =[NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.cnblogs.com/mddblog/"]];
//    // 3.加载网页
    [webView loadRequest:request];
//    [webView loadFileURL:[NSURL fileURLWithPath:@"/Users/userName/Desktop/bigIcon.png"] allowingReadAccessToURL:[NSURL fileURLWithPath:@"/Users/userName/Desktop/bigIcon.png"]];
    // 最后将webView添加到界面
    [self.view addSubview:webView];
}
/// 模拟器加载mac本地文件
- (void)loadLocalFile {
    // 1.创建webview，并设置大小，"20"为状态栏高度
    WKWebView *webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 20, self.view.frame.size.width, self.view.frame.size.height - 20)];
    // 2.创建url  userName：电脑用户名
    NSURL *url = [NSURL fileURLWithPath:@"/Users/userName/Desktop/bigIcon.png"];
    // 3.加载文件
    [webView loadFileURL:url allowingReadAccessToURL:url];
    // 最后将webView添加到界面
    [self.view addSubview:webView];
}
- (void)addSubViews {
    [self addBottomViewButtons];
    
    [self.view addSubview:self.searchBar];
    
    [self.view addSubview:self.wkWebView];
}

- (void)addBottomViewButtons {
    // 记录按钮个数
    int count = 0;
    // 添加按钮
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setTitle:@"后退" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor colorWithRed:249 / 255.0 green:102 / 255.0 blue:129 / 255.0 alpha:1.0] forState:UIControlStateNormal];
    [button setTitleColor:[UIColor lightGrayColor] forState:UIControlStateHighlighted];
    [button setTitleColor:[UIColor lightGrayColor] forState:UIControlStateDisabled];
    [button.titleLabel setFont:[UIFont systemFontOfSize:15]];
    button.tag = ++count;    // 标记按钮
    [button addTarget:self action:@selector(onBottomButtonsClicled:) forControlEvents:UIControlEventTouchUpInside];
    [self.bottomView addSubview:button];
    self.backBtn = button;
    
    button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setTitle:@"前进" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor colorWithRed:249 / 255.0 green:102 / 255.0 blue:129 / 255.0 alpha:1.0] forState:UIControlStateNormal];
    [button setTitleColor:[UIColor lightGrayColor] forState:UIControlStateHighlighted];
    [button setTitleColor:[UIColor lightGrayColor] forState:UIControlStateDisabled];
    [button.titleLabel setFont:[UIFont systemFontOfSize:15]];
    button.tag = ++count;
    [button addTarget:self action:@selector(onBottomButtonsClicled:) forControlEvents:UIControlEventTouchUpInside];
    [self.bottomView addSubview:button];
    self.forwardBtn = button;
    
    button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setTitle:@"重新加载" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor colorWithRed:249 / 255.0 green:102 / 255.0 blue:129 / 255.0 alpha:1.0] forState:UIControlStateNormal];
    [button setTitleColor:[UIColor lightGrayColor] forState:UIControlStateHighlighted];
    [button setTitleColor:[UIColor lightGrayColor] forState:UIControlStateDisabled];
    [button.titleLabel setFont:[UIFont systemFontOfSize:15]];
    button.tag = ++count;
    [button addTarget:self action:@selector(onBottomButtonsClicled:) forControlEvents:UIControlEventTouchUpInside];
    [self.bottomView addSubview:button];
    self.reloadBtn = button;
    
    button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setTitle:@"Safari" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor colorWithRed:249 / 255.0 green:102 / 255.0 blue:129 / 255.0 alpha:1.0] forState:UIControlStateNormal];
    [button setTitleColor:[UIColor lightGrayColor] forState:UIControlStateHighlighted];
    [button setTitleColor:[UIColor lightGrayColor] forState:UIControlStateDisabled];
    [button.titleLabel setFont:[UIFont systemFontOfSize:15]];
    button.tag = ++count;
    [button addTarget:self action:@selector(onBottomButtonsClicled:) forControlEvents:UIControlEventTouchUpInside];
    [self.bottomView addSubview:button];
    self.browserBtn = button;
    // 统一设置frame
    [self setupBottomViewLayout];
}
- (void)setupBottomViewLayout
{
    int count = 4;
    CGFloat btnW = 80;
    CGFloat btnH = 30;
    
    CGFloat btnY = (self.bottomView.bounds.size.height - btnH) / 2;
    // 按钮间间隙
    CGFloat margin = (self.bottomView.bounds.size.width - btnW * count) / count;
    
    CGFloat btnX = margin * 0.5;
    self.backBtn.frame = CGRectMake(btnX, btnY, btnW, btnH);
    
    btnX = self.backBtn.frame.origin.x + btnW + margin;
    self.forwardBtn.frame = CGRectMake(btnX, btnY, btnW, btnH);
    
    btnX = self.forwardBtn.frame.origin.x + btnW + margin;
    self.reloadBtn.frame = CGRectMake(btnX, btnY, btnW, btnH);
    
    btnX = self.reloadBtn.frame.origin.x + btnW + margin;
    self.browserBtn.frame = CGRectMake(btnX, btnY, btnW, btnH);
}
/// 刷新按钮是否允许点击
- (void)refreshBottomButtonState {
    if ([self.wkWebView canGoBack]) {
        self.backBtn.enabled = YES;
    } else {
        self.backBtn.enabled = NO;
    }
    
    if ([self.wkWebView canGoForward]) {
        self.forwardBtn.enabled = YES;
    } else {
        self.forwardBtn.enabled = NO;
    }
}
/// 按钮点击事件
- (void)onBottomButtonsClicled:(UIButton *)sender {
    switch (sender.tag) {
        case 1:
        {
            [self.wkWebView goBack];
            [self refreshBottomButtonState];
        }
            break;
        case 2:
        {
            [self.wkWebView goForward];
            [self refreshBottomButtonState];
        }
            break;
        case 3:
            [self.wkWebView reload];
            break;
        case 4:
            [[UIApplication sharedApplication] openURL:self.wkWebView.URL];
            break;
        default:
            break;
    }
}

#pragma mark - WKWebView WKNavigationDelegate 相关
/// 是否允许加载网页 在发送请求之前，决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
    
    NSString *urlString = [[navigationAction.request URL] absoluteString];
    
    urlString = [urlString stringByRemovingPercentEncoding];
    //    NSLog(@"urlString=%@",urlString);
    // 用://截取字符串
    NSArray *urlComps = [urlString componentsSeparatedByString:@"://"];
    if ([urlComps count]) {
        // 获取协议头
        NSString *protocolHead = [urlComps objectAtIndex:0];
        NSLog(@"protocolHead=%@",protocolHead);
    }
    decisionHandler(WKNavigationActionPolicyAllow);
}


#pragma mark - searchBar代理方法
/// 点击搜索按钮
- (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar {
    // 创建url
    NSURL *url = nil;
    NSString *urlStr = searchBar.text;
    
    // 如果file://则为打开bundle本地文件，http则为网站，否则只是一般搜索关键字
    if([urlStr hasPrefix:@"file://"]){
        NSRange range = [urlStr rangeOfString:@"file://"];
        NSString *fileName = [urlStr substringFromIndex:range.length];
        url = [[NSBundle mainBundle] URLForResource:fileName withExtension:nil];
        // 如果是模拟器加载电脑上的文件，则用下面的代码
//        url = [NSURL fileURLWithPath:fileName];
    }else if(urlStr.length>0){
        if ([urlStr hasPrefix:@"http://"]) {
            url=[NSURL URLWithString:urlStr];
        } else {
            urlStr=[NSString stringWithFormat:@"http://www.baidu.com/s?wd=%@",urlStr];
        }
        urlStr = [urlStr stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
        url=[NSURL URLWithString:urlStr];
        
    }
    NSURLRequest *request=[NSURLRequest requestWithURL:url];
    
    // 加载请求页面
    [self.wkWebView loadRequest:request];
}
#pragma mark - 懒加载
- (UIView *)bottomView {
    if (_bottomView == nil) {
        UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, kScreenHeight - kBottomViewH, kScreenWidth, kBottomViewH)];
        view.backgroundColor = [UIColor colorWithRed:230/255.0 green:230/255.0 blue:230/255.0 alpha:1];
        [self.view addSubview:view];
        _bottomView = view;
    }
    return _bottomView;
}
- (UISearchBar *)searchBar {
    if (_searchBar == nil) {
        UISearchBar *searchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(0, 20, kScreenWidth, kSearchBarH)];
        searchBar.delegate = self;
        searchBar.text = @"http://www.cnblogs.com/mddblog/";
        _searchBar = searchBar;
        
    }
    return _searchBar;
}

- (WKWebView *)wkWebView {
    if (_wkWebView == nil) {
        WKWebView *webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 20 + kSearchBarH, kScreenWidth, kScreenHeight - 20 - kSearchBarH - kBottomViewH)];
        webView.navigationDelegate = self;
//                webView.scrollView.scrollEnabled = NO;
        
        //        webView.backgroundColor = [UIColor colorWithPatternImage:self.image];
        // 允许左右划手势导航，默认允许
        webView.allowsBackForwardNavigationGestures = YES;
        _wkWebView = webView;
    }

    return _wkWebView;
}


@end