extract value from UIpickerview as variable - ios

Question

so i have this code for a UIpickerview and i want to get the value selected as a variable to use later, i tried using a variable gravity but it says "initialisation of variable gravity was never used...." here's my code:
var g = ["9.807", "3.711"]
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return g.count
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return g[row]
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
var gravity = Float(g[row])
}

Answer 1

You need to declare the var outside of the scope of your method:
var gravity: Float?
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
gravity = Float(g[row])
}
A local variable scope is limited to the method and as you don't use it within the method you get a warning for that.
This is Swift not Javascript :)

Answer 2

Your gravity var is local, so the given warning makes total sense (i.e., its scope is limited to the given function).
You should use the following UIPickerView method to get the currently selected index:
func selectedRow(inComponent component: Int) -> Int
For instance:
let gIndex = pickerView.selectedRow(inComponent: 0)
let gValue = Float(g[gIndex])!
Note that you do not even need to implement the didSelectRow delegate method to get this information.
As correctly pointed out in the comments, you of course need to declare and bind your UIPickerView to an instance var of your view controller:
#IBOutlet weak var pickerView: UIPickerView!

Answer 3

To use pickerView, first mention its DataSource and Delegate.
UIPickerViewDataSource, UIPickerViewDelegate
Now create this by right clicking on pickerView -> to the ViewContoller.swfit.You will get like:
#IBOutlet var pickerView: [UIPickerView]!
Create an array which contains the content you want to show in pickerView. Just like this:
var array:[String] = ["David","Mikel","Akhil","Akshay","Zlatan"]
Now you have to use pickerView functions. These functions can only be used if you mention DataSource and Delegate in class. The functions are:
// number of rows or number of components
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
// number of rows that we have to set
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return array.count
}
// set title in picker view according to the elements
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return array[row]
}
// when an element is selected, store in a string
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
pickerString = array[row]
print(pickerString) // pickerString is String type. You can create this, to show the content selected.
}