centering text in a UILabel with an NSAttributedString - ios

Question

Going through some basic improvements to a application I am working on. Still new to the iOS swift development scene. I figured that the lines of text in my code would automatically be centered because I set the label to center. After a little bit of research I discovered this is not the case. How would I align code like this to center:
let atrString = try NSAttributedString(
data: assetDetails!.cardDescription.dataUsingEncoding(NSUTF8StringEncoding)!,
options: [NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType],
documentAttributes: nil)
assetDescription.attributedText = atrString

Answer 1

You need to create a paragraph style specifying center alignment, and set that paragraph style as an attribute on your text. Example playground:
import UIKit
import PlaygroundSupport
let style = NSMutableParagraphStyle()
style.alignment = NSTextAlignment.center
let richText = NSMutableAttributedString(string: "Going through some basic improvements to a application I am working on. Still new to the iOS swift development scene. I figured that the lines of text in my code would automatically be centered because I set the label to center.",
attributes: [ NSParagraphStyleAttributeName: style ])
// In Swift 4, use `.paragraphStyle` instead of `NSParagraphStyleAttributeName`.
let label = UILabel(frame: CGRect(x: 0, y: 0, width: 200, height: 400))
label.backgroundColor = UIColor.white
label.attributedText = richText
label.numberOfLines = 0
PlaygroundPage.current.liveView = label
Result:
Since you're parsing an HTML document to create your attributed string, you'll need to add the attribute after creation, like this:
let style = NSMutableParagraphStyle()
style.alignment = NSTextAlignment.center
let richText = try NSMutableAttributedString(
data: assetDetails!.cardDescription.data(using: String.Encoding.utf8)!,
options: [NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType],
documentAttributes: nil)
richText.addAttributes([ NSParagraphStyleAttributeName: style ],
range: NSMakeRange(0, richText.length))
// In Swift 4, use `.paragraphStyle` instead of `NSParagraphStyleAttributeName`.
assetDescription.attributedText = richText
Update for Swift 4
In Swift 4, attribute names are now of type NSAttributeStringKey and the standard attribute names are static members of that type. So you can add the attribute like this:
richText.addAttribute(.paragraphStyle, value: style, range: NSMakeRange(0, richText.length))

Answer 2

In Swift 4.1 :
let style = NSMutableParagraphStyle()
style.alignment = NSTextAlignment.center
lbl.centerAttributedText = NSAttributedString(string: "Total Balance",attributes: [.paragraphStyle: style])
(edited for code block)

Answer 3

You can use this utility function to do all common configuration for label
#discardableResult
public func DULabel(text: String, frame: CGRect = .zero, parent:UIView? = nil , font:UIFont, textColor:UIColor = .black, numOfLines:Int = 0 ,textAlignment: NSTextAlignment = .center,lineSpaceing:CGFloat = 0, cb: ((UILabel)->Void)? = nil )-> UILabel! {
let label = UILabel()
label.frame = frame
label.font = font
label.textColor = textColor
label.textAlignment = textAlignment
label.numberOfLines = numOfLines
if( lineSpaceing == 0 ){
label.text = text
}
else {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = lineSpaceing
paragraphStyle.alignment = textAlignment
let attrString = NSMutableAttributedString(string: text)
attrString.addAttribute(.paragraphStyle, value:paragraphStyle, range:NSMakeRange(0, attrString.length))
label.attributedText = attrString
}
if let parent = parent {
parent.addSubview(label)
}
cb?(label)
return label
}