Passing custom NSObject between View Controller Swift

Question

Hi,
My question is how do I pass a custom object between View Controllers. 
Assume there is FirstViewController and SecondViewController. Also assume there is an NSObject called CustomObject
I'd imagine using segues to pass the data but the problem is the initialisation of the custom object. For example:
```
//In FirstViewController
.
.
.
let index = 0
let dataToPass = array[index] as CustomObject
self.performSegueWithIdentifier("segue", sender: dataToPass)
.
.
.
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "segue"{
            let destinationVC:FirstViewController = segue.destinationViewController as FirstViewController
            destinationVC.temp= sender
        }
    }
.
.
.
```
My problem in FirstViewController is that the line "destinationVC.temp= sender" gives me the following error:
"Cannot convert the expression's type '()' to type 'CustomObject' "
```
//In SecondViewController
.
.
.
class SecondViewController:UIViewController{
let temp:CustomObject
.
.
.
}
```
In SecondViewController, I get the error:
"Class SecondViewController has no initialisers". TO fix this error, xcode keeps prompting me to implement 
```
    required init(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
```
But I don't actually know what this does 
Any help would be much appreciated!

Jason Wayne · Answer

The problem in the FirstViewController in the segue method is as what the error is saying. The sender is type AnyObject, which cannot be converted to type NSObject, CutomObject. 
In your SecondViewController, you are not instantiating the constant. You are just declaring the type of the constant which is CutomObject, which is type NSObject. Try, changing it to let temp = CustomObject() or var temp = CustomObject(). 
In your FirstViewController, you should consider creating a variable or constant called temp as well. That way, throughout the entire code, just use self.temp. 
Once that is done, in your segue method in the FirstViewController, assign destination.temp = self.temp. 
That should work. Hope it points you to the right direction. =]

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Nick Sint

Nick Sint

Passing custom NSObject between View Controller Swift

1 Answer

Jason Wayne

Jason Wayne