iOS开发 之 WebView点击图片看大图效果

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

标签： 代码

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