c 读取html text,Converting HTML text into plain text using Objective-C

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问题:

I have huge NSString with HTML text inside. The length of this string is more then 3.500.000 characters. How can i convert this HTML text to NSString with plain text inside. I was using scanner , but it works too slowly. Any idea ?

回答1:

It depends what iOS version you are targeting. Since iOS7 there is a built-in method that will not only strip the HTML tags, but also put the formatting to the string:

Xcode 9/Swift 4 if let htmlStringData = htmlString.data(using: .utf8), let attributedString = try? NSAttributedString(data: htmlStringData, options: [.documentType : NSAttributedString.DocumentType.html], documentAttributes: nil) { print(attributedString) }

You can even create an extension like this: extension String { var htmlToAttributedString: NSAttributedString? { guard let data = self.data(using: .utf8) else { return nil } do { return try NSAttributedString(data: data, options: [.documentType : NSAttributedString.DocumentType.html, .characterEncoding: String.Encoding.utf8.rawValue], documentAttributes: nil) } catch { print("Cannot convert html string to attributed string: \(error)") return nil } } }

Note that this sample code is using UTF8 encoding. You can even create a function instead of computed property and add the encoding as a parameter.

Swift 3 let attributedString = try NSAttributedString(data: htmlString.dataUsingEncoding(NSUTF8StringEncoding)!, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil)

Objective-C [[NSAttributedString alloc] initWithData:[htmlString dataUsingEncoding:NSUTF8StringEncoding] options:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType, NSCharacterEncodingDocumentAttribute: [NSNumber numberWithInt:NSUTF8StringEncoding]} documentAttributes:nil error:nil];

If you just need to remove everything between < and > (dirty way!!!), which might be problematic if you have these characters in the string, use this: - (NSString *)stringByStrippingHTML { NSRange r; NSString *s = [[self copy] autorelease]; while ((r = [s rangeOfString:@"]+>" options:NSRegularExpressionSearch]).location != NSNotFound) s = [s stringByReplacingCharactersInRange:r withString:@""]; return s; }

回答2:

I resolve my question with scanner, but i use it not for all the text. I use it for every 10.000 text part, before i concatenate all parts together. My code below -(NSString *)convertHTML:(NSString *)html { NSScanner *myScanner; NSString *text = nil; myScanner = [NSScanner scannerWithString:html]; while ([myScanner isAtEnd] == NO) { [myScanner scanUpToString:@"" intoString:&text] ; html = [html stringByReplacingOccurrencesOfString:[NSString stringWithFormat:@"%@>", text] withString:@""]; } // html = [html stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]; return html; }

回答3:

For Swift Language , NSAttributedString(data:(htmlString as! String).dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true )!, options:[NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType, NSCharacterEncodingDocumentAttribute: NSNumber(unsignedLong: NSUTF8StringEncoding)], documentAttributes: nil, error: nil)!

回答4:

- (NSString *)stringByStrippingHTML:(NSString *)inputString { NSMutableString *outString; if (inputString) { outString = [[NSMutableString alloc] initWithString:inputString]; if ([inputString length] > 0) { NSRange r; while ((r = [outString rangeOfString:@"]+>| " options:NSRegularExpressionSearch]).location != NSNotFound) { [outString deleteCharactersInRange:r]; } } } return outString; }

回答5:

Did you try something like that below, Not sure if it will faster as you did before using scanner please check:- //String which contains html tags NSString *htmlString=[NSString stringWithFormat:@"%@",@"right onto Kennington Park Rd/A3Continue to follow A3