File Scope? Swift Delegates and Protocols - ios

Question

I'm working on building a new Swift app roughly based off an old Obj-c app. I'm currently working on the delegates
Here is what my obj-c code looked like in the .h file
#interface MyAppViewController : CustomViewController
#property (nonatomic, weak) id<MyAppViewControllerDelegate> delegate;
#end
#protocol MyAppViewControllerDelegate <NSObject>
- (void)myAppViewController:(MyAppViewController *)controller loggedInStudent: (MYStudent *)student;
- (void)myAppViewControllerWantsSignUp:(MyAppViewController *)controller;
#end
In SWIFT I did:
class MyAppViewController: CustomViewController {
var delegate: MyAppViewControllerDelegate?
protocol MyAppViewControllerDelegate{
func myAppViewController(controller: MyAppViewController, loggedInStudent: MYStudent)
func myAppViewControllerWantsSignUp(controller: MyAppViewController)
I've done a lot of reading and study on this, so I thought I was doing it basically right (totally new to swift though... so)
I'm getting this error though, "Declaration is only valid in file scope" on the protocol MyAppViewControllerDelegate {
I assumed this had something to do with declaring it within the class, so I moved it out, only now my code within the class doesn't recognize the delegate variable I declared..
Any ideas?

Answer 1

Should be this:
protocol MyAppViewControllerDelegate {
func myAppViewController(controller: MyAppViewController, loggedInStudent: MYStudent)
func myAppViewControllerWantsSignUp(controller: MyAppViewController)
}
class MyAppViewController: CustomViewController {
var delegate: MyAppViewControllerDelegate?
}
Although, if you're following a common pattern where the object that owns MyAppViewController is also its delegate, this may cause memory issues. You can use class typing to allow weak delegation like so:
protocol MyAppViewControllerDelegate : class {
func myAppViewController(controller: MyAppViewController, loggedInStudent: MYStudent)
func myAppViewControllerWantsSignUp(controller: MyAppViewController)
}
class MyAppViewController: CustomViewController {
weak var delegate: MyAppViewControllerDelegate?
}
This is slightly limiting because it requires you to use a class for your delegate, but it will help avoid retain cycles :)

Answer 2

From what I see in your source code is that you've declared your protocol inside of your class.
Just declare the protocol outside of the class declaration and you'll be fine.
Update:
The default access level is set to internal which is defined as
Internal access enables entities to be used within any source file from their defining module, >but not in any source file outside of that module. You typically use internal access when >defining an app’s or a framework’s internal structure.
In contrast to Objective-C or C you don't need a forward declaration if the implementation haven't happened before the usage.
Source: The Swift Programming Language, Access Control