Why is UITextView's text not being replaced? - ios

Question

I have a short bit of code that is meant to take a string, find words in a library, and replace them from a random array of other words. For some reason, when I hit the button, nothing happens! I made it work in the playground, so what am I doing wrong?
App code:
import UIKit
extension Array {
func randomItem() -> T {
let index = Int(arc4random_uniform(UInt32(self.count)))
return self[index]
}
}
extension String {
func replace(target: String, withString: String) -> String
{
return self.stringByReplacingOccurrencesOfString(target, withString: withString, options: NSStringCompareOptions.LiteralSearch, range: nil)
}
}
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
maintext.text = "The Dog Chases the Ball"
self.submit.setTitle("Change It", forState: UIControlState.Normal)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBOutlet var maintext: UITextView!
#IBOutlet var submit: UIButton!
#IBAction func submitTapped(sender: UIButton) {
self.submit.setTitle("Again", forState: UIControlState.Normal)
var AllWords = maintext.text
var WordsArray = AllWords.componentsSeparatedByString(" ")
var Dog = ["Pup", "Canine", "Wolf"]
var Ball = ["Frisbee", "Stick", "Car"]
AllWords.replace("Dog", withString: Dog.randomItem()).replace("Ball", withString: Ball.randomItem())
}
}
Play Ground:
import UIKit
import Foundation
extension Array {
func randomItem() -> T {
let index = Int(arc4random_uniform(UInt32(self.count)))
return self[index]
}
}
extension String
{
func replace(target: String, withString: String) -> String
{
return self.stringByReplacingOccurrencesOfString(target, withString: withString, options: NSStringCompareOptions.LiteralSearch, range: nil)
}
}
var Text = "The Dog Loves to Chase the Ball"
//: Old Text Loaded as an array
var AllWords = Text.componentsSeparatedByString(" ")
//: New Word Library
let Dog = ["Pup", "Canine", "Wolf"]
let Ball = ["Frisbee", "Stick", "Car"]
for element in AllWords {
Text.replace(element, withString: Dog.randomItem())
Text.replace(element, withString: Ball.randomItem())
}
Text.replace("Dog", withString: Dog.randomItem()).replace("Ball", withString: Ball.randomItem())
Thank you!

Answer 1

You're copying maintext.text into AllWords and then replacing the text in AllWords. AllText now has a copy of what's in maintext.text, but is not pointing to the textview's text property. After replacing the text in AllWords, you should assign AllWords to maintext.text:
var AllWords = maintext.text
var WordsArray = AllWords.componentsSeparatedByString(" ")
var Dog = ["Pup", "Canine", "Wolf"]
var Ball = ["Frisbee", "Stick", "Car"]
AllWords.replace("Dog", withString: Dog.randomItem()).replace("Ball", withString: Ball.randomItem())
maintext.text = AllWords // You need set the textview's text here
If that still fails, try jumping back on the main thread when setting the text:
dispatch_async(dispatch_get_main_queue(), { () -> Void in
maintext.text = AllWords
})

Answer 2

The type String in Swift is a value type that means that any change creates a new instance of String.
The string of the text view is left unchanged.
So after the replace task you have to reassign the value to the text view
maintext.text = AllWords
PS: please name variables with a first lowercase letter