how to append Attributed Text String with Attributed String in Swift

I want to append an Attributed Text with another Attributed Text in Swift. Please provide any sample code for appending operation of two attributed String in Swift.

Use NSMutableAttributedString to achieve that.

Example

Swift 5

let yourAttributes = [NSForegroundColorAttributeName: UIColor.black, NSFontAttributeName: UIFont.systemFont(ofSize: 15)]
let yourOtherAttributes = [NSForegroundColorAttributeName: UIColor.red, NSFontAttributeName: UIFont.systemFont(ofSize: 25)]

let partOne = NSMutableAttributedString(string: "This is an example ", attributes: yourAttributes)
let partTwo = NSMutableAttributedString(string: "for the combination of Attributed String!", attributes: yourOtherAttributes)

partOne.append(partTwo) 

Swift 3

let yourAttributes = [NSForegroundColorAttributeName: UIColor.black, NSFontAttributeName: UIFont.systemFont(ofSize: 15)]
let yourOtherAttributes = [NSForegroundColorAttributeName: UIColor.red, NSFontAttributeName: UIFont.systemFont(ofSize: 25)]

let partOne = NSMutableAttributedString(string: "This is an example ", attributes: yourAttributes)
let partTwo = NSMutableAttributedString(string: "for the combination of Attributed String!", attributes: yourOtherAttributes)

let combination = NSMutableAttributedString()

combination.append(partOne)
combination.append(partTwo)

combination represents your final string which contains both formattings provided by yourAttributes and yourOtherAttributes

Even older

let yourAttributes = [NSForegroundColorAttributeName: UIColor.blackColor(), NSFontAttributeName: UIFont.systemFontOfSize(15)]
let yourOtherAttributes = [NSForegroundColorAttributeName: UIColor.redColor(), NSFontAttributeName: UIFont.systemFontOfSize(25)]

let partOne = NSMutableAttributedString(string: "This is an example ", attributes: yourAttributes)
let partTwo = NSMutableAttributedString(string: "for the combination of Attributed String!", attributes: yourOtherAttributes)

let combination = NSMutableAttributedString()

combination.appendAttributedString(partOne)
combination.appendAttributedString(partTwo) 

@glace's answer, modified to avoid empty NSMutableAttributedString declaration. Valid in Swift 3.1:

let yourAttributes = [NSForegroundColorAttributeName: UIColor.blackColor(), NSFontAttributeName: UIFont.systemFontOfSize(15)]
let yourOtherAttributes = [NSForegroundColorAttributeName: UIColor.redColor(), NSFontAttributeName: UIFont.systemFontOfSize(25)]

let partOne = NSMutableAttributedString(string: "This is an example ", attributes: yourAttributes)
let partTwo = NSMutableAttributedString(string: "for the combination of Attributed String!", attributes: yourOtherAttributes)

partOne.append(partTwo)

partOne is then your final string with all the attributes. No intermediate "combiner" necessary.

Swift 4

let yourAttributes: [NSAttributedString.Key: Any] = [.foregroundColor: UIColor.black, .font: UIFont.systemFont(ofSize: 15)]
let yourOtherAttributes: [NSAttributedString.Key: Any] = [.foregroundColor: UIColor.red, .font: UIFont.systemFont(ofSize: 25)]

let partOne = NSMutableAttributedString(string: "This is an example ", attributes: yourAttributes)
let partTwo = NSMutableAttributedString(string: "for the combination of Attributed String!", attributes: yourOtherAttributes)

partOne.append(partTwo)

Swift 5

As per "glace" answer, I just update font attribute and swift version.

    let boldFontAttributes = [NSAttributedString.Key.foregroundColor: UIColor.black, NSAttributedString.Key.font: UIFont.boldSystemFont(ofSize: 17)]
    let normalFontAttributes = [NSAttributedString.Key.foregroundColor: UIColor.darkGray, NSAttributedString.Key.font: UIFont.systemFont(ofSize: 15)]
    let partOne = NSMutableAttributedString(string: "This is an example ", attributes: boldFontAttributes)
    let partTwo = NSMutableAttributedString(string: "for the combination of Attributed String!", attributes: normalFontAttributes)

    let combination = NSMutableAttributedString()
    
    combination.append(partOne)
    combination.append(partTwo)
    lblUserName.attributedText = combination

using extension,

extension NSMutableAttributedString{
    func getAttributedStringByAppending(attributedString:NSMutableAttributedString) -> NSMutableAttributedString{
        let newAttributedString = NSMutableAttributedString()
        newAttributedString.append(self)
        newAttributedString.append(attributedString)
        return newAttributedString
    }
}

Usage: attributedString1, attributedString2 are two NSMutableAttributedString, then

let combinedAttributedString = attributedString1.getAttributedStringByAppending(attributedString: attributedString2)

Swift 5

You can create the different attributes:

let kString1Attributes = NSAttributedString.attributes(foregroundColor: UIColor.white)
let kString2Attributes = NSAttributedString.attributes(foregroundColor: UIColor.black)

Define your attributed strings:

let attrString1 = NSAttributedString(string: "my string" + " ",
                                     attributes: kString1Attributes)
let attrString2 = NSAttributedString(string: "string 2",
                                     attributes: kString2Attributes)

Include them in an array and combine them all together:

let combinedAttrString = [attrString1, attrString2].joined()