Highlighting
About this widget
Displays the highlighted attributes of your search results.
Examples
Consider a movies index.
Each movie record consists of two fields: title and year.
Algolia’s response to the query “red” could look like:
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{
"title": "The Shawshank Redemption",
"year": 1994,
"objectID": "439817390",
"_highlightResult": {
"title": {
"value": "The Shawshank <em>Red</em>emption",
"matchLevel": "full",
"fullyHighlighted": false,
"matchedWords": [
"red"
]
}
}
}
Consider the _highlightResult’s value: "The Shawshank <em>Red</em>emption". The part of the string to highlight is marked with <em> tags or your custom tags.
HighlightedString is constructed with a raw tagged string, detects the tags and creates a TaggedString. This tagged string provides following properties:
input: the input string.output: the input string without its tags.taggedRanges: a list of ranges defining highlighted ranges inoutput.
You can build a highlighted string in iOS is with an NSAttributedString. InstantSearch provides HighlightedString and NSAttributedString extensions to make this easy.
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let rawHighlightedString = "The Shawshank <em>Red</em>emption"
let highlightedString = HighlightedString(string: rawHighlightedString)
// Attributes to apply for a highlighted part of the string
let highLightingAttributes: [NSAttributedString.Key: Any] = [
.foregroundColor: UIColor.red
]
// Create attributed string highlighted part of which is red
let attributedString = NSAttributedString(highlightedString: highlightedString, attributes: attributes)
The produced NSAttributedString can be assigned to a UIKit component that supports it.
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let attributedString: NSAttributedString = ...
let label: UILabel = ...
label.attributedText = attributedString
The Hit wrapper structure uses the HighlightedString structure.
You can extract a highlighted string for an attribute using its hightlightedString(forKey key: String) function.
Example:
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/* JSON search response
{
"title": "The Shawshank Redemption",
"year": 1994,
"objectID": "439817390",
"_highlightResult": {
"title": {
"value": "The Shawshank <em>Red</em>emption",
"matchLevel": "full",
"fullyHighlighted": false,
"matchedWords": [
"red"
]
},
}
}
*/
struct Movie: Codable {
let title: String
let year: Int
}
let movieHit: Hit<Movie> = ... /* parse JSON response */
let highlightedMovieTitle: HighlightedString? = movieHit.hightlightedString(forKey: "title")
You can read more about usage of the Hit wrapper structure in the Hits reference.
