SwiftUI, using a button to multiply values inside textfields

Question

I am new to coding, Swift and Xcode. I am in the process of creating an application which will multiply 3 values (length, width, height) to calculate the volume of a specific object.

The end goal of the app is to be able to calculate the volume of many objects and having a "total" value which will accumulatively add up the volumes for you. Getting a start on my app I have a layout sorted which includes the three text fields where the user will punch in the values (length, width, height) and a text which has has "Total =". I have successfully made the text fields accept doubles by using:

TextField("length", value: $length, formatter: NumberFormatter())

I am using a button to execute the multiplication using:

Button(action: {self.equation = self.length * self.width * self.thickness})

And a Text where the value will show:

Text("Total= \(equation)")

Unfortunately, when I run the app, insert values into each of the text fields and hit the button the "Total=" Text does not execute the action of the button. Just trying to figure out where I have gone wrong.

Answer 1

TextField with formatter does not apply input string till explicit commit, so try the following

extension UIApplication {  // just helper extension
    static func endEditing() {
        UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to:nil, from:nil, for:nil)
    }
}

and

Button(action: {
    UIApplication.endEditing()    // << here !!
    self.equation = self.length * self.width * self.thickness
})