Check if an NSString is an html string?

Question

I am creating an application that should display a list of strings, the string is returned from the server and can be either an html or not. I am currently setting the text inside a UILabel. to do that i am using the below

    NSMutableAttributedString *attributedTitleString = [[NSMutableAttributedString alloc] initWithData:[title dataUsingEncoding:NSUnicodeStringEncoding] options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];
cell.label.attributedText =attributedTitleString;

When the text is an html, everything work perfectly since the font and alignments are returned inside the html. The issue is occurring when the text is a normal text. The font, text alignment, text size and others are not being respected anymore.

So how can I check if the text is an html string or not? I will be using the following in case of normal text:

cell.label.text =title;

I have tried to search on forums but still didn't get any answer for my issue.

Answer 1

This is working fine, you need to put:

cell.label. attributedText = title; incase of normal text too.

As It is working fine. Run the below code.

//If HTML Text

NSString *htmlstr = `@"This is <font color='red'>simple</font>"`;

NSMutableAttributedString *attributedTitleString = [[NSMutableAttributedString alloc] initWithData:[htmlstr dataUsingEncoding:NSUnicodeStringEncoding] options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];

textField.attributedText =attributedTitleString;

textField.font = [UIFont fontWithName:@"vardana" size:20.0];

//If Normal text.

NSString *normalStr = @"This is Renuka";

NSMutableAttributedString *NorAttributedTitleString = [[NSMutableAttributedString alloc] initWithData:[normalStr dataUsingEncoding:NSUnicodeStringEncoding] options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];

textField.attributedText = NorAttributedTitleString;

textField.font = [UIFont fontWithName:@"vardana" size:20.0];

Answer 2

You can check if your string contains html tag :

// iOS8 +

NSString *string = @"<TAG>bla bla bla html</TAG>";

if ([string containsString:@"<TAG"]) {
    NSLog(@"html string");
} else {
    NSLog(@"no html string");
}

// iOS7 +

NSString *string = @"<TAG>bla bla bla html</TAG>";

if ([string rangeOfString:@"<TAG"].location != NSNotFound) {
    NSLog(@"html string");
} else {
    NSLog(@"no html string");
}

Answer 3

Since the syntax and structure of HTML and XML is quite similar, you can utilize XMLDocument to check whether a given data object is HTML or plain text.

So data is from the type Data and is returned by an URLSession dataTask.

// Default to plain text
var options : [NSAttributedString.DocumentReadingOptionKey: Any] = [.documentType: NSAttributedString.DocumentType.plain]

// This will succeed for HTML, but not for plain text                
if let _ = try? XMLDocument(data: data, options: []) {
     options[.documentType] = NSAttributedString.DocumentType.html
}

guard let string = try? NSAttributedString(data: data, options: options, documentAttributes: nil) else { return }

---

Update

The above method works sort of. I had trouble with some HTML not creating an XML document. For the moment I have a different solution, that I don't really like. As the symptom is that we get only one line back in the attributed string, simply check for that and create a new attributed string if there is only one line.

var options : [NSAttributedString.DocumentReadingOptionKey: Any] = [.documentType: NSAttributedString.DocumentType.html]

guard var string = try? NSAttributedString(data: data, options: options, documentAttributes: nil) else { return }

if string.string.split(separator: "\n").count == 1 {
    options[.documentType] = NSAttributedString.DocumentType.plain
    guard let tempString = try? NSAttributedString(data: data, options: options, documentAttributes: nil) else { return }
    string = tempString
}