原理：
1.JS调用OC
每次webview执行跳转时都会被iOS给拦截，执行下面函数获得系统允许。
因此可以根据跳转信息转给系统，执行相应功能，比如打开相册等。
// 网页中的每一个请求都会被触发
-(BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
2.OC调用JS：通过webview执行js函数实现
[webView stringByEvaluatingJavaScriptFromString:@"postStr();"];
HTML：
<html> <head> <meta http-equiv="Content-Type" content="text/html"; charset="UTF-8"/> <title>HTML中用JS调用OC方法</title> <script> function getInfo(name) { window.location = "/getInfo/"+name; } function postStr(){ return "I am script"; } </script> </head> <body> <h1 onclick="getInfo('openMyAlbum')">打开相册</h1> <br> <h1 onclick="getInfo('openMyCamera')">打开相机</h1> </body> </html>
OC：
#import "ViewController.h" @interface ViewController (){ UIWebView *webView; UIActivityIndicatorView *activityIndicator; } @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; [self.view setBackgroundColor:[UIColor lightGrayColor]]; webView = [[UIWebView alloc] initWithFrame:CGRectMake(0,22, CGRectGetWidth(self.view.bounds), CGRectGetHeight(self.view.bounds)-66)]; NSURLRequest *request =[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://dong14.sinaapp.com/testhtml.html"]]; [self.view addSubview: webView]; [webView loadRequest:request]; [webView setDelegate:self]; // Do any additional setup after loading the view, typically from a nib. UIButton *clkbtn=[[UIButton alloc]initWithFrame:CGRectMake(0, CGRectGetHeight(self.view.bounds)-44, 88, 44)]; [clkbtn setTitle:@"调用JS" forState:UIControlStateNormal]; [clkbtn setBackgroundColor:[UIColor redColor]]; [clkbtn addTarget:self action:@selector(jsclk) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:clkbtn]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } // 网页中的每一个请求都会被触发 -(BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType { // 每次跳转时候判断URL if([request.mainDocumentURL.relativePath isEqualToString:@"/getInfo/openMyAlbum"]) { NSLog(@"openMyAlbum"); [self openMyAlbum]; return NO; } // 每次跳转时候判断URL if([request.mainDocumentURL.relativePath isEqualToString:@"/getInfo/openMyCamera"]) { NSLog(@"openMyCamera"); [self openMyCamera]; return NO; } return YES; } -(void)openMyAlbum { UIImagePickerController *vc = [[UIImagePickerController alloc]init]; vc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary; [self presentViewController:vc animated:YES completion:nil]; } -(void)openMyCamera { UIImagePickerController *vc = [[UIImagePickerController alloc]init]; vc.sourceType = UIImagePickerControllerSourceTypeCamera; [self presentViewController:vc animated:YES completion:nil]; } -(void)jsclk{ NSString *str = [webView stringByEvaluatingJavaScriptFromString:@"postStr();"]; NSLog(@"JS返回值：%@",str); } - (void) webViewDidStartLoad:(UIWebView *)webView { //创建UIActivityIndicatorView背底半透明View UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 2, CGRectGetWidth(self.view.bounds), CGRectGetHeight(self.view.bounds)-66)]; [view setTag:108]; [view setBackgroundColor:[UIColor blackColor]]; [view setAlpha:0.5]; [self.view addSubview:view]; activityIndicator = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 32.0f, 32.0f)]; [activityIndicator setCenter:view.center]; [activityIndicator setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleWhite]; [view addSubview:activityIndicator]; [activityIndicator startAnimating]; NSLog(@"webViewDidStartLoad"); } - (void) webViewDidFinishLoad:(UIWebView *)webView { [activityIndicator stopAnimating]; UIView *view = (UIView*)[self.view viewWithTag:108]; [view removeFromSuperview]; NSLog(@"webViewDidFinishLoad"); } - (void) webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error { [activityIndicator stopAnimating]; UIView *view = (UIView*)[self.view viewWithTag:108]; [view removeFromSuperview]; NSLog(@"didFailLoadWithError:%@", error); }