Set Delegate in a mixed language project - objective-c

Question

I have an XCode6 mixed-language project, combining Swift and Objective C.
I created a Swift-based SingleView application, then added 2 Objective-C files, having contents as below:
Singleton.h
#import <Foundation/Foundation.h>
#protocol SingletonDelegate <NSObject>
#optional
- (void)methodCalled;
#end
#interface Singleton : NSObject
#property (weak, nonatomic) id <SingletonDelegate> singletonDelegate;
+ (id)sharedSingleton;
- (void)method;
#end
Singleton.m
#import "Singleton.h"
static Singleton *shared = nil;
#implementation Singleton
- (id)init {
self = [super init];
if (self) {
}
return self;
}
#pragma mark - Interface
+ (Singleton *)sharedSingleton {
static dispatch_once_t pred;
dispatch_once(&pred, ^{
shared = [[Singleton alloc] init];
});
return shared;
}
- (void)method {
[self.singletonDelegate methodCalled];
}
#end
After setting up bridging header file as XCode suggested, I added #import "Singleton.h" into it.
In ViewController.swift, I tried to set singletonDelegate but always failed:
import UIKit
class ViewController: UIViewController, SingletonDelegate {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
Singleton.sharedSingleton().singletonDelegate = self // FAILED HERE!!!
Singleton.sharedSingleton().method()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
The error message is:
Cannot assign to the result of this expression
Could any one show me how to fix this? (I am new in integrating Objective-C into Swift project)
Thanks in advance,

Answer 1

Create a class variable. Then set its delegate.
let singleton: Singleton = Singleton.sharedSingleton()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
singleton.singletonDelegate = self
//Singleton.sharedSingleton().singletonDelegate = self // FAILED HERE!!!
//Singleton.sharedSingleton().method()
}
fun methodCalled() {
//This method gets called from the Singleton class through the delegate
}