Replace substring of NSAttributedString with another NSAttributedString

I want to replace a substring (e.g. @"replace") of an NSAttributedString with another NSAttributedString.

I am looking for an equivalent method to NSString's stringByReplacingOccurrencesOfString:withString: for NSAttributedString.

Solution 1:

1. Convert your attributed string into an instance of NSMutableAttributedString.

2. The mutable attributed string has a mutableString property. According to the documentation:

   "The receiver tracks changes to this string and keeps its attribute mappings up to date."

   So you can use the resulting mutable string to execute the replacement with replaceOccurrencesOfString:withString:options:range:.

Solution 2:

In my case, the following way was the only (tested on iOS9):

NSAttributedString *attributedString = ...;
NSAttributedString *anotherAttributedString = ...; //the string which will replace

while ([attributedString.mutableString containsString:@"replace"]) {
        NSRange range = [attributedString.mutableString rangeOfString:@"replace"];
        [attributedString replaceCharactersInRange:range  withAttributedString:anotherAttributedString];
    }

Of course it will be nice to find another better way.

Solution 3:

Here is how you can change the string of NSMutableAttributedString, while preserving its attributes:

Swift:

// first we create a mutable copy of attributed text 
let originalAttributedText = nameLabel.attributedText?.mutableCopy() as! NSMutableAttributedString

// then we replace text so easily
let newAttributedText = originalAttributedText.mutableString.setString("new text to replace")

Objective-C:

NSMutableAttributedString *newAttrStr = [attribtedTxt.mutableString setString:@"new string"];

Solution 4:

Swift 4: Updated sunkas excellent solution to Swift 4 and wrapped in "extension". Just clip this into your ViewController (outside the class) and use it.

extension NSAttributedString {
    func stringWithString(stringToReplace: String, replacedWithString newStringPart: String) -> NSMutableAttributedString
    {
        let mutableAttributedString = mutableCopy() as! NSMutableAttributedString
        let mutableString = mutableAttributedString.mutableString
        while mutableString.contains(stringToReplace) {
            let rangeOfStringToBeReplaced = mutableString.range(of: stringToReplace)
            mutableAttributedString.replaceCharacters(in: rangeOfStringToBeReplaced, with: newStringPart)
        }
        return mutableAttributedString
    }
}

Solution 5:

With Swift 4 and iOS 11, you can use one of the 2 following ways in order to solve your problem.

#1. Using NSMutableAttributedString replaceCharacters(in:with:) method

NSMutableAttributedString has a method called replaceCharacters(in:with:). replaceCharacters(in:with:) has the following declaration:

Replaces the characters and attributes in a given range with the characters and attributes of the given attributed string.

func replaceCharacters(in range: NSRange, with attrString: NSAttributedString)

The Playground code below shows how to use replaceCharacters(in:with:) in order to replace a substring of an NSMutableAttributedString instance with a new NSMutableAttributedString instance:

import UIKit

// Set initial attributed string
let initialString = "This is the initial string"
let attributes = [NSAttributedStringKey.foregroundColor : UIColor.red]
let mutableAttributedString = NSMutableAttributedString(string: initialString, attributes: attributes)

// Set new attributed string
let newString = "new"
let newAttributes = [NSAttributedStringKey.underlineStyle : NSUnderlineStyle.styleSingle.rawValue]
let newAttributedString = NSMutableAttributedString(string: newString, attributes: newAttributes)

// Get range of text to replace
guard let range = mutableAttributedString.string.range(of: "initial") else { exit(0) }
let nsRange = NSRange(range, in: mutableAttributedString.string)

// Replace content in range with the new content
mutableAttributedString.replaceCharacters(in: nsRange, with: newAttributedString)

#2. Using NSMutableString replaceOccurrences(of:with:options:range:) method

NSMutableString has a method called replaceOccurrences(of:with:options:range:). replaceOccurrences(of:with:options:range:) has the following declaration:

Replaces all occurrences of a given string in a given range with another given string, returning the number of replacements.

func replaceOccurrences(of target: String, with replacement: String, options: NSString.CompareOptions = [], range searchRange: NSRange) -> Int

The Playground code below shows how to use replaceOccurrences(of:with:options:range:) in order to replace a substring of an NSMutableAttributedString instance with a new NSMutableAttributedString instance:

import UIKit

// Set initial attributed string
let initialString = "This is the initial string"
let attributes = [NSAttributedStringKey.foregroundColor : UIColor.red]
let mutableAttributedString = NSMutableAttributedString(string: initialString, attributes: attributes)

// Set new string
let newString = "new"

// Replace replaceable content in mutableAttributedString with new content
let totalRange = NSRange(location: 0, length: mutableAttributedString.string.count)
_ = mutableAttributedString.mutableString.replaceOccurrences(of: "initial", with: newString, options: [], range: totalRange)

// Get range of text that requires new attributes
guard let range = mutableAttributedString.string.range(of: newString) else { exit(0) }
let nsRange = NSRange(range, in: mutableAttributedString.string)

// Apply new attributes to the text matching the range
let newAttributes = [NSAttributedStringKey.underlineStyle : NSUnderlineStyle.styleSingle.rawValue]
mutableAttributedString.setAttributes(newAttributes, range: nsRange)