How can we transfer data between classes when using swift programming language

Question

With Objective-C we could transfer data to an array at an UIView class from ViewController using a method.

In an UIView class we were using something like this

 float values[10];

-(void) getValue:(float) value index:(int) index {

    values[index] = value       

   }

But when we try doing a similar thing with Swift such as

    var values   : [CGFloat] = [10]

       func getValue (value:CGFloat, index:Int) {

       values [index] = value

    }

We are getting " fatal error: Array index out of range error " or if we use

       var values   : [CGFloat] = [10]
       var index = 0

       func getValue (value:CGFloat) {

       values.append = value

       ++index
    }

We are not getting error message but whenever we use setNeedsDisplay() array values are being set to initial values which is 10 for this example.

Till now we are unable to convert Objective-C UIView classes like that to Swift one.

Answer 1

Yes, after studying some more Swift I found the answer to my question.

Using static variable in the UIView class is the answer.

Define variable like that in UIView class

struct StructToChange {

  static  var varToChange = 1

}

Write a function to change variable value like this in UIView class.

func getIt (newValue:Int) {

    StructToChange.varToChange = newValue

}

Call the function in a controller class this way

  let valueChanger = AnyUIViewClass()
  valueChanger.getIt ( 10 )

This is it you changed the value of variable and you can use it as parameter in your " override func drawRect(rect: CGRect) { } "

Answer 2

First:

var values : [CGFloat] = [10]

That line says that values is a variable array of CGFloat values that currently holds a single value of 10. Therefore, only index 0 actually exists.

Also:

func getValue(value:CGFloat, index:Int) {
    values [index] = value
}

Never mind the fact that you have put this on the UIView class, never mind that you have a method named "getValue" that actually sets a value...

EDIT:

I found a better solution:

var values = Array<Float>(count:10, repeatedValue: 0)

func getValue(value: Float, index: Int) {
    values[index] = value
}

The above is the direct Swift equivalent to the Objective-C code you posted in your question.

Frankly, I think you should take a step back and find a better way to solve the problem you think this code is solving. As it stands it doesn't make a whole lot of sense.

Answer 3

var values : [CGFloat] = [10]

In swift, this will create an array of CGFloat with one element: 10.0, not 10 elements. so values.count is one

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