iOS开发 之 WebView点击图片看大图效果详解手机开发

项目里面需要实现，点击webView里面的图片，看大图并且能够放大缩小效果，在此记录下实现过程。

• 在webViewDelegate里面添加如下代码：

• - (void)webViewDidFinishLoad:(UIWebView *)aWebView { 
   
      //调整字号 
      NSString *str = @"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '95%'"; 
      [webView stringByEvaluatingJavaScriptFromString:str]; 
       
      //js方法遍历图片添加点击事件 返回图片个数 
      static  NSString * const jsGetImages = 
      @"function getImages(){/ 
      var objs = document.getElementsByTagName(/"img/");/ 
                                               for(var i=0;i<objs.length;i++){/ 
                                                   objs[i].onclick=function(){/ 
                                                       document.location=/"myweb:imageClick:/"+this.src;/ 
                                                   };/ 
                                               };/ 
                                               return objs.length;/ 
                                               };"; 
       
      [webView stringByEvaluatingJavaScriptFromString:jsGetImages];//注入js方法 
       
      //注入自定义的js方法后别忘了调用 否则不会生效（不调用也一样生效了，，，不明白） 
      NSString *resurlt = [webView stringByEvaluatingJavaScriptFromString:@"getImages()"]; 
      //调用js方法 
  //    NSLog(@"---调用js方法--%@  %s  jsMehtods_result = %@",self.class,__func__,resurlt); 
  }

• - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{ 
      //将url转换为string 
      NSString *requestString = [[request URL] absoluteString]; 
  //    NSLog(@"requestString is %@",requestString); 
       
      //hasPrefix 判断创建的字符串内容是否以pic:字符开始 
      if ([requestString hasPrefix:@"myweb:imageClick:"]) { 
          NSString *imageUrl = [requestString substringFromIndex:@"myweb:imageClick:".length]; 
  //        NSLog(@"image url------%@", imageUrl); 
           
          if (bgView) { 
              //设置不隐藏，还原放大缩小，显示图片 
              bgView.hidden = NO; 
              imgView.frame = CGRectMake(10, 10, SCREEN_WIDTH-40, 220); 
              [imgView setImageWithURL:[NSURL URLWithString:imageUrl] placeholderImage:LOAD_IMAGE(@"house_moren")]; 
          } 
          else 
              [self showBigImage:imageUrl];//创建视图并显示图片 
           
          return NO; 
      } 
      return YES; 
  }

• 创建放大图片的视图

• #pragma mark 显示大图片 
  -(void)showBigImage:(NSString *)imageUrl{ 
      //创建灰色透明背景，使其背后内容不可操作 
      bgView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT)]; 
      [bgView setBackgroundColor:[UIColor colorWithRed:0.3 
                                                 green:0.3 
                                                  blue:0.3 
                                                 alpha:0.7]]; 
      [self.view addSubview:bgView]; 
       
      //创建边框视图 
      UIView *borderView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH-20, 240)]; 
      //将图层的边框设置为圆脚 
      borderView.layer.cornerRadius = 8; 
      borderView.layer.masksToBounds = YES; 
      //给图层添加一个有色边框 
      borderView.layer.borderWidth = 8; 
      borderView.layer.borderColor = [[UIColor colorWithRed:0.9 
                                                      green:0.9 
                                                       blue:0.9 
                                                      alpha:0.7] CGColor]; 
      [borderView setCenter:bgView.center]; 
      [bgView addSubview:borderView]; 
       
      //创建关闭按钮 
      UIButton *closeBtn = [UIButton buttonWithType:UIButtonTypeCustom]; 
  //    [closeBtn setImage:[UIImage imageNamed:@"close.png"] forState:UIControlStateNormal]; 
      closeBtn.backgroundColor = [UIColor redColor]; 
      [closeBtn addTarget:self action:@selector(removeBigImage) forControlEvents:UIControlEventTouchUpInside]; 
      [closeBtn setFrame:CGRectMake(borderView.frame.origin.x+borderView.frame.size.width-20, borderView.frame.origin.y-6, 26, 27)]; 
      [bgView addSubview:closeBtn]; 
       
      //创建显示图像视图 
      imgView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 10, CGRectGetWidth(borderView.frame)-20, CGRectGetHeight(borderView.frame)-20)]; 
      imgView.userInteractionEnabled = YES; 
      [imgView setImageWithURL:[NSURL URLWithString:imageUrl] placeholderImage:LOAD_IMAGE(@"house_moren")]; 
      [borderView addSubview:imgView]; 
       
      //添加捏合手势 
      [imgView addGestureRecognizer:[[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(handlePinch:)]]; 
       
  }

• 实现关闭和捏合手势的方法

• //关闭按钮 
  -(void)removeBigImage 
  { 
      bgView.hidden = YES; 
  } 
   
  - (void) handlePinch:(UIPinchGestureRecognizer*) recognizer 
  { 
      //缩放:设置缩放比例 
      recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale); 
      recognizer.scale = 1; 
  }

效果图如下