Detailed explanation and implementation code of interaction between javascript and IOS ObjectC

#import "ViewController.h"

@interface ViewController ()

@property (weak, nonatomic) IBOutlet UIWebView *webView;

@end
- (void)viewDidLoad {
  [super viewDidLoad];
  // 设置webView的代理
  self.webView.delegate = self;

  // 加载网页数据
  NSURL *URL = [NSURL URLWithString:@"http://m.dianping.com/tuan/deal/5501525"];
//  NSURL *URL = [NSURL URLWithString:@"https://www.hao123.com/?tn=93321723_hao_pg"];
  NSURLRequest *request = [NSURLRequest requestWithURL:URL];
  [self.webView loadRequest:request];
}

/// 网页加载完成之后调用的代理方法 : JS注入 : OC调用JS代码
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
  // 用于拼接JS代码的字符串
  NSMutableString *stringM = [NSMutableString string];

  // 拼接移除顶部导航的JS代码
  [stringM appendString:@"var headerTag = document.getElementsByTagName('header')[0]; 
  headerTag.parentNode.removeChild(headerTag);"];
  // 拼接移除橙色按钮的JS代码
  [stringM appendString:@"var footerBtnTag = document.getElementsByClassName('footer-btn-fix')[0]; 
  footerBtnTag.parentNode.removeChild(footerBtnTag);"];
  // 拼接移除底部布局的JS代码
  [stringM appendString:@"var footerTag = document.getElementsByClassName('footer')[0]; 
  footerTag.parentNode.removeChild(footerTag);"];
  // 拼接给img标签添加点击事件的JS代码
  [stringM appendString:@"var imgTag = document.getElementsByTagName('figure')[0].children[0]; 
  imgTag.onclick = function(){window.location.href='https://www.baidu.com'};"];

  // 这个方法就是UIWebView提供的.专门做JS注入的方法
  [webView stringByEvaluatingJavaScriptFromString:stringM];
}

imgTag.onclick = function(){window.location.href='https://www.baidu.com‘}

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
  // 获取拦截到的所有的请求
  NSString *URLString = request.URL.absoluteString;
  //https://m.baidu.com/?from=1015143h
  //  NSLog(@"%@",URLString);

  if ([URLString isEqualToString:@"https://m.baidu.com/?from=1015143h"]) {
    NSLog(@"我点击的是imgTag");

    // 当我知道点击的是imgTag时,自动push
    //http://www.csdn.net/

    NSURL *URL = [NSURL URLWithString:@"http://www.csdn.net/"];
    NSURLRequest *request = [NSURLRequest requestWithURL:URL];
    [self.webView loadRequest:request];
//    TestViewController *testVC = [[TestViewController alloc] init];
//    [self.navigationController pushViewController:testVC animated:YES];

    // 因为这个地址是无效地址.不需要加载的
    return NO;
  }

  // 返回YES的作用 : 表示你拦截到的请求,允许正常的发送出去;反之,不允许拦截到的请求发送出去
  return YES;
}