iOS开发网络篇 —— OC加载HTML代码

html代码

图1

样式一："<p><img src="/upload/image/20170609/1496978712941664.jpg" title="1496978712941664.jpg" alt="7.jpg"/>测试内容信息无错</p>"
样式二：<h1 style="font-size: 32px; font-weight: bold; border-bottom: 2px solid rgb(204, 204, 204); 
padding: 0px 4px 0px 0px; text-align: left; margin: 0px 0px 10px;">你好 <a href="https://baidu.com" target="_self" title="五六千可">
了的好莱坞去任何</a><img src="http://imgsrc.baidu.com/imgad/pic/item/caef76094b36acaf0accebde76d98d1001e99ce7.jpg"/></h1><p><br/></p>

图2

一、情景1：加载到UILabel上面（转换成富文本即可）

 //1.将字符串转化为标准HTML字符串
  NSString *str1 = [self htmlEntityDecode:htmlString];
//2.将HTML字符串转换为attributeString
    NSAttributedString * attributeStr = [self attributedStringWithHTMLString:str1];
 //3.使用label加载html字符串并将label添加到view上
    self.label.attributedText = attributeStr;
    [self.label setFrame:CGRectMake(100,100,200,300)];
    [self.view addSubview:self.label];
//------html 转换成字符串
//将 &lt 等类似的字符转化为HTML中的“<”等 
- (NSString *)htmlEntityDecode:(NSString *)string
{
    string = [string stringByReplacingOccurrencesOfString:@""" withString:@"""];
    string = [string stringByReplacingOccurrencesOfString:@"'" withString:@"'"];
    string = [string stringByReplacingOccurrencesOfString:@"<" withString:@"<"];
    string = [string stringByReplacingOccurrencesOfString:@">" withString:@">"];
    string = [string stringByReplacingOccurrencesOfString:@"&" withString:@"&"]; // Do this last so that, e.g. @"<" goes to @"<" not @"<"
    return string;
}
//------ 将html转换成富文本
//将HTML字符串转化为NSAttributedString富文本字符串
- (NSAttributedString *)attributedStringWithHTMLString:(NSString *)htmlString
{
    NSDictionary *options = @{ NSDocumentTypeDocumentAttribute : NSHTMLTextDocumentType,
                               NSCharacterEncodingDocumentAttribute :@(NSUTF8StringEncoding) };
    NSData *data = [htmlString dataUsingEncoding:NSUTF8StringEncoding];
    return [[NSAttributedString alloc] initWithData:data options:options documentAttributes:nil error:nil];
}
//图2 中的样式2 可以会出现显示空白，可以通过去除html标签来处理
//去掉 HTML 字符串中的标签
- (NSString *)filterHTML:(NSString *)html
{　　NSScanner * scanner = [NSScanner scannerWithString:html];
    NSString * text = nil;
    while([scanner isAtEnd]==NO)
    {
        //找到标签的起始位置
        [scanner scanUpToString:@"<" intoString:nil];
        //找到标签的结束位置
        [scanner scanUpToString:@">" intoString:&text];
        //替换字符
        html = [html stringByReplacingOccurrencesOfString:[NSString stringWithFormat:@"%@>",text] withString:@""];
    }
    return html;
}

二、情景2：加载到UIWebView上面（替换html中部分的字符）

    //1.将字符串转化为标准HTML字符串，(此处的字符串不是标准的标签的HTML字符串,将字符串转换成标准的HTML字符串，这样才可以进行HTML字符串的加载)
    NSString *str1 = [self htmlEntityDecode:htmlString];//调用情景1的方法
   //2.UIWebView 加载HTML字符串
    UIWebView * webView = [[UIWebView alloc] initWithFrame:CGRectMake(20, 150, self.view.frame.size.width-20, 400)];
    [webView loadHTMLString:str1 baseURL:nil];
    [self.view addSubview:webView];
 

三、缓存html用RNCachingURLProtocol库。