实现一个分享扩展插件，功能是从Safari网页中截取当前网页的图片内容

基本的步骤总结在下面：

1.创建一个JS文件，命名为MyJavascriptFile.js，文件的功能是解析safari网页内容，获取到网页中的所有图片节点，解析从图片的URL，返回所有图片URL拼接而成的字符串。
JS中主要用到run: function(arguments){}这个方法来处理抓取数据的逻辑，处理抓取到的数据调用 arguments.completionFunction({ "webImages": imageArrStr }); 这个方法把数据返回，"webImages"这个key可以自定义，在第三步的原生层OC代码中需要用到这个key把JS层抓取到的数据取出来，然后可以对这些图片数据进行保存、上传等需要的操作了。

MyJavascriptFile.js文件内容

var BuscapeClass = function() {};BuscapeClass.prototype = {run: function(arguments) {var imageArray = new Array();var objs = document.getElementsByTagName("img");for(var i=0;i<objs.length;i++){if(imageArray.indexOf(objs[i].src) == -1){imageArray.push(objs[i].src);}}var imageArrStr = imageArray.join('+');// Pass the baseURI of the webpage to the extension.arguments.completionFunction({ "webImages": imageArrStr });},// Note that the finalize function is only available in iOS.finalize: function(arguments) {// arguments contains the value the extension provides in [NSExtensionContext completeRequestReturningItems:completion:].// In this example, the extension provides a color as a returning item.// document.body.style.backgroundColor = arguments["bgColor"];var bestOffer = arguments["bestOffer"];alert("A melhor oferta é da loja\n" + bestOffer["sellername"] + " por " + bestOffer["price"]);}
};// The JavaScript file must contain a global object named "ExtensionPreprocessingJS".
var ExtensionPreprocessingJS = new BuscapeClass;

2.在info.plis文件中把创建的JS文件进行配置，配置如下：
配置的源码

  <key>NSExtension</key><dict><key>NSExtensionAttributes</key><dict><key>NSExtensionActivationRule</key><string>SUBQUERY (extensionItems,$extensionItem,SUBQUERY ($extensionItem.attachments,$attachment,(ANY $attachment.registeredTypeIdentifiers UTI-CONFORMS-TO "public.url"|| ANY $attachment.registeredTypeIdentifiers UTI-CONFORMS-TO "public.image"|| ANY $attachment.registeredTypeIdentifiers UTI-CONFORMS-TO "public.plain-text")).@count &gt;= $extensionItem.attachments.@count
).@count &gt;= 1</string><key>NSExtensionJavaScriptPreprocessingFile</key><string>MyJavascriptFile</string></dict><key>NSExtensionMainStoryboard</key><string>MainInterface</string><key>NSExtensionPointIdentifier</key><string>com.apple.share-services</string></dict>

3.原生层OC代码中处理JS抓取的数据，主要用到这两句，把数据取出来"webImages"这个key要和JS中定义的KEY一致

NSDictionary *results = jsDict[NSExtensionJavaScriptPreprocessingResultsKey];
NSString* result = [results objectForKey:@"webImages"];

完整的处理代码

- (void)fetchDataFromWebContent {__weak typeof(self) weakSelf = self;//获取inputItems，在这里itemProvider是你要分享的图片NSArray* extensionItems = self.extensionContext.inputItems;for (NSExtensionItem *extensionItem in extensionItems) {NSMutableArray* tmpTypeImageArr = [NSMutableArray array];NSMutableArray* tmpTypePropertyListArr = [NSMutableArray array];NSArray* attachments = extensionItem.attachments;// 处理attachmentsfor (NSItemProvider *itemProvider in attachments) {// 注入JS获取图片数据数据if ([itemProvider hasItemConformingToTypeIdentifier:(NSString *)kUTTypePropertyList]) {[itemProvider loadItemForTypeIdentifier:(NSString *)kUTTypePropertyList options:nil completionHandler:^(NSDictionary *jsDict, NSError *error) {NSLog(@"jsDict: %@", jsDict);dispatch_async(dispatch_get_main_queue(), ^{// Get javascript resultNSDictionary *results = jsDict[NSExtensionJavaScriptPreprocessingResultsKey];NSString* result = [results objectForKey:@"webImages"];BMLog(@"=== webImages ===%@", result);NSArray* tmpArr = [weakSelf handleImages:result];if (tmpArr.count > 0) {[tmpTypePropertyListArr addObjectsFromArray:tmpArr];}[weakSelf handleResult:tmpTypePropertyListArr];});}];}}}
}- (NSArray*)handleImages:(NSString*)imagesStr {NSMutableArray* mUrlArray = [NSMutableArray arrayWithArray:[imagesStr componentsSeparatedByString:@"+"]];NSMutableArray* tmpUrls = [NSMutableArray array];for (int i = mUrlArray.count-1; i>=0; i--) {NSString* url = mUrlArray[i];// 过滤空的和jpg的图像if (![url isEmptyOrWhitespace]) {// 在这里处理图片的URL}}NSLog(@"mUrlArray = %@   tmpUrls = %@", mUrlArray, tmpUrls);return tmpUrls;
}

参考资料：
App Extension Programming Guide