Swift/Objective-C: How to call a view-controller-method from another class

Question

Lets say I have a class called FooController. It will at some point in time call the method bar(str: String) owend by the second class BarController. BarController is a subclass of NSViewController and has an IBOutlet. This outlet is connected to a NSButton.

bar simply changes the text of the button to some string like "Example".

My first approach was to create a new instance of BarController and then calling the method.

var bc = BarController()
bc.bar("Example")

My problem is, that the new instance is not connectet to the interface and so the IBOutlet becomes nil.

func bar(str: String) {
    myButton.title = str // myButton is nil
}

Answer 1

1) Connect the button to a property in a class that is instantiated at your application launch, for example your AppDelegate. Let us say you create a property called aButton. ---> Therefore you keep a track of your object

AppDelegate.h

@interface AppDelegate
@property(weak) IBOutlet NSButton *aButton;
@end

AppDelegate.m
@implementation AppDelegate
-(void)applicationDidFinishLaunching:(NSNotification*)notification
{
     BarController* controller = [BarController controllerForButton:aButton];
}
@end

2) When you create your BarController object, create a class method that would set a property _button to aButton. --> Therefore your objects knows the adress of your button.

BarController.h
@interface BarController
{
    NSButton *_button;
}
@end

BarController.m
@implementation BarController

+(BarController*)controllerForButton:(NSButton*)button{
    return[[BarController alloc] initWithButton:button];
}

-(void)initWithButton:(NSButton*)button{
    self = [super init];
    if (self)
    {
        _button = button;
    }
}