#import "ViewController.h"    @interface ViewController () <UIWebViewDelegate>    @property(nonatomic,weak)UIWebView* web;  @end    @implementation ViewController    - (void)viewDidLoad {      [super viewDidLoad];            [self _setTextField];            [self _loadWebView];        }    #pragma mark - 设置输入框  - (void)_setTextField{      self.tf.clearButtonMode=UITextFieldViewModeWhileEditing;  }    #pragma mark - 加载WebView  - (void)_loadWebView{      UIWebView* web=[[UIWebView alloc] init];      web.frame=CGRectMake(0,self.view.frame.size.height,self.view.frame.size.width,self.view.frame.size.height-42 );      self.web=web;      web.delegate=self;      [self.view addSubview:web];              }    #pragma mark - 放弃第一响应  -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{      [self.tf resignFirstResponder];        }    #pragma mark - Action  - (IBAction)backAction:(id)sender {      [self.web goBack];  //    self.web.frame=CGRectMake(0,self.view.frame.size.height,self.view.frame.size.width,self.view.frame.size.height-42 );        }    - (IBAction)forwardAction:(id)sender {      [self.web goForward];      self.web.frame=CGRectMake(0,20,self.view.frame.size.width,self.view.frame.size.height-50);  }    - (IBAction)undoAction:(id)sender {      [self.web stopLoading];  }    - (IBAction)refreshAction:(id)sender {      [self.web reload];  }    - (IBAction)searchAction:(id)sender {      [self.tf resignFirstResponder];            self.web.frame=CGRectMake(0,20,self.view.frame.size.width,self.view.frame.size.height-60);        [self _sendRequest];  }    #pragma mark - UIWebViewDelegate  - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{                  return YES;  }    - (void)webViewDidStartLoad:(UIWebView *)webView{    }    - (void)webViewDidFinishLoad:(UIWebView *)webView{  //    NSLog(@"%d===%d",[webView canGoBack],[webView canGoForward]);      self.backBt.enabled=[webView canGoBack];      self.forwardBt.enabled=[webView canGoForward];      self.refresh.enabled=([webView canGoBack] ||[webView canGoForward]);  }    - (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error{      NSLog(@"%@",error);    }    - (void)_sendRequest{      //http://www.baidu.com      NSURL* url=[NSURL URLWithString:self.tf.text];      NSURLRequest* request=[NSURLRequest requestWithURL:url];      [self.web loadRequest:request];  }    @end