Text not displaying value of Var. Swift - swift

Question

I'm a beginner, but I'm trying to display the "valueWeWantToGrab" to a text field but is not showing the result.
this is my code to display someone's Instagram follower amount
struct ContentView: View {
#State var valueWeWantToGrab = ""
var body: some View {
let baseUrl = "http://www.instagram.com/"
let username = ""
let url = URL(string: baseUrl + username)!
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let data = data else {
print("data was nil")
return
}
guard let htmlString = String(data: data, encoding: .utf8) else {
print("couldn't cast data into String")
return
}
print(htmlString)
let leftSideString = """
edge_followed_by":{"count":
"""
let rightSideString = """
},"followed_by_viewer
"""
guard
let leftSideRange = htmlString.range(of: leftSideString)
else {
print("couldn't find left range")
return
}
guard
let rightSideRange = htmlString.range(of: rightSideString)
else {
print("couldn't find right range")
return
}
let rangeOfTheData = leftSideRange.upperBound..<rightSideRange.lowerBound
var valueWeWantToGrab = htmlString[rangeOfTheData]
print(valueWeWantToGrab) // prints the follower count: 19093
}
Text(valueWeWantToGrab)
}
}

Answer 1

The issue is that you declare the variable valueWeWantToGrab twice: Once at the top annotated with #State and once towards the bottom within the getter function of the body variable.
What you actually want to do at the bottom is assigning to the variable declared at the top instead of declaring a new variable by removing var from the line var valueWeWantToGrab = htmlString[rangeOfTheData]. Doing that, you also have to wrap htmlString[rangeOfTheData] with a String initializer (String()) as htmlString[rangeOfTheData] gives you a value of type Substring, not a value of type String. This is the result:
...
let rangeOfTheData = leftSideRange.upperBound..<rightSideRange.lowerBound
valueWeWantToGrab = String(htmlString[rangeOfTheData])
print(valueWeWantToGrab) // prints the follower count: 19093
...
Also, to make your code a little cleaner (though not required to make it work), it might be a good idea to move the code that loads the data to a dedicated method instead of putting it in the getter of the body variable (as a general rule of thumb, try to only put UI elements in the body of SwiftUI Views and do the business logic somewhere else - that will help you to keep your code clean and readable). You can then call the method in the initializer of your ContentView. This comes with the benefit that you can then reuse that method elsewhere - for example to implement a refresh button in the future. This is what the final result might look like:
struct ContentView: View {
#State var valueWeWantToGrab = ""
var body: some View {
Text(valueWeWantToGrab)
}
init() {
loadFollowerCount()
}
private func loadFollowerCount() {
let baseUrl = "http://www.instagram.com/"
let username = ""
let url = URL(string: baseUrl + username)!
URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let data = data else {
print("data was nil")
return
}
guard let htmlString = String(data: data, encoding: .utf8) else {
print("couldn't cast data into String")
return
}
print(htmlString)
let leftSideString = """
edge_followed_by":{"count":
"""
let rightSideString = """
},"followed_by_viewer
"""
guard
let leftSideRange = htmlString.range(of: leftSideString)
else {
print("couldn't find left range")
return
}
guard
let rightSideRange = htmlString.range(of: rightSideString)
else {
print("couldn't find right range")
return
}
let rangeOfTheData = leftSideRange.upperBound..<rightSideRange.lowerBound
valueWeWantToGrab = String(htmlString[rangeOfTheData])
print(valueWeWantToGrab) // prints the follower count: 19093
}
}
}
One final tip in case you come from a web development background (which is what I am guessing): vars in Swift are different from vars in JavaScript. In JavaScript, the redeclaration would have overridden the previous value of valueWeWantToGrab and your code would have worked. However, in Swift, this actually declares a new, different variable in the local scope of the getter function. Have a look at the Swift docs to find out more about how variable declarations work in Swift.