一：URL的读取,保存,本地读取保存
1:后台返回的html的话，去加载这些数据,进行展示：

        NSURL *url = [NSURL URLWithString:@"URL"];
        NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
        //[_webView loadHTMLString:_modelArticle.url baseURL:url];
        [_webView loadRequest:request];
        [self addTitleViewWithTitle:_modelArticle.title];

        如果加载的url存在,但是后台需要插入js,去掉广告之类的
        - (void)webViewDidFinishLoad:(UIWebView *)webView {
          //_modelJs.content  是js代码
             [_webView stringByEvaluatingJavaScriptFromString:_modelJs.content];
              }

2:下面是保存PDF到本地:
//判断pdf是否存在，如果不存在进行保存
-(BOOL)TxtisFileExist:(NSString *)fileName {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path = [paths objectAtIndex:0];
NSString *filePath = [path stringByAppendingPathComponent:fileName];
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOL result = [fileManager fileExistsAtPath:filePath];
NSLog(@"这个文件已经存在：%@",result?@"是的":@"不存在");
return result;
}
3:保存数据
需要UIWebView的扩展类进行存储转NSdata

import "UIWebView+ConverToData.h"

@implementation UIWebView (ConverToData)

• (NSData *)converToPDF{
  UIViewPrintFormatter *fmt = [self viewPrintFormatter];
  UIPrintPageRenderer *render = [[UIPrintPageRenderer alloc] init];
  [render addPrintFormatter:fmt startingAtPageAtIndex:0];
  CGRect page;
  page.origin.x=0;
  page.origin.y=0;
  page.size.width=600;
  page.size.height=768;

  CGRect printable=CGRectInset( page, 50, 50 );
  [render setValue:[NSValue valueWithCGRect:page] forKey:@"paperRect"];
  [render setValue:[NSValue valueWithCGRect:printable] forKey:@"printableRect"];

  NSMutableData * pdfData = [NSMutableData data];
  UIGraphicsBeginPDFContextToData( pdfData, CGRectZero, nil );

  for (NSInteger i=0; i < [render numberOfPages]; i++)
  {
  UIGraphicsBeginPDFPage();
  CGRect bounds = UIGraphicsGetPDFContextBounds();
  [render drawPageAtIndex:i inRect:bounds];

  }
  UIGraphicsEndPDFContext();
  return pdfData;
  }

//调用上面的方法

//注意了,别用汉语名称去保存，可以用唯一标识进行保存

    NSData *data = [_webView converToPDF];
    NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"Documents/%@.pdf",[self transform:strName]]];
    BOOL result = [data writeToFile:path atomically:YES];
    if (result) {  @"下载成功"}

4:如果保存下来后直接进行读取本地PDF
如果存在： 调用下面的代码 记住你传过的名字 然后进行UIWeView加载就OK了

• (void)readPDF:(NSString *)str
  {
  NSString *filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
  NSString *imageFilePath = [filePath stringByAppendingPathComponent:str];
  NSURL *urlttt = [NSURL fileURLWithPath:imageFilePath];
  NSURLRequest *request = [NSURLRequest requestWithURL:urlttt];
  [_webView loadRequest:request];
  }

二：后台数据是PDF文件如何操作

//这个是下载后台返回的pdf文件进行下载
//首先是判断文件的存没有存在，然后进行数据的下载或者读取

• (void)download:(NSString *)strurl path:(NSString *)pathName
  {
  if (![self TxtisFileExist:[NSString stringWithFormat:@"%@.pdf",pathName]]) {
  NSString *urlString = strurl;
  NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
  NSURLRequest *request = [NSURLRequest requestWithURL:url];
  AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];

    NSURLSessionDownloadTask *task = [manager downloadTaskWithRequest:request progress:^(NSProgress * _Nonnull downloadProgress) {
        
    } destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString * documentsDirectory = [paths lastObject];
        NSString * path = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.pdf",[self transform:pathName]]];
        
        return [NSURL fileURLWithPath:path];
    } completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePath, NSError * _Nullable error) {
        
        if (error == nil) {
           [self.view showToastMessage:@"下载成功"];
        }else{
            [self.view showToastMessage:@"下载失败,请检查网络或者PDF文件过大"];
            [self addRefreshButton:self.view refreshBlock:^{}];
        }
    }];
    [task resume];
  

  }else{

    NSString *filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *imageFilePath = [filePath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.pdf",[self transform:pathName]]];
    NSURL *urlttt = [NSURL fileURLWithPath:imageFilePath];
    NSURLRequest *request = [NSURLRequest requestWithURL:urlttt];
    [_webView loadRequest:request];
  

  }
  }