Accessing Swift Extension From Objective-C

Question

I'm having trouble accessing my swift extension from objective-c.

I have the following code in a .swift file:

extension NSDictionary {
    func dictionaryAsJsonString() -> NSString {
        var err: NSError?
        var data = NSJSONSerialization.dataWithJSONObject(self, options: NSJSONWritingOptions.PrettyPrinted, error: &err)
        var string = NSString(data: data, encoding: NSUTF8StringEncoding)
        return string
    }
}

I'm expecting to be able to do the following in my .m file:

[dictionary dictionaryAsJsonString];

but it can't find my method and doesn't autocomplete.

I know my imports are working fine because I'm able to access my other swift objects.

Answer 1

In short:

File configuration setup:

CustomClass.h
CustomClass.m
CustomClassExtension.swift

In CustomClassExtension:

@objc extension CustomClass
{
    func method1() 
    {
        ...
    }
}

In any other class:

self.customClass = [[CustomClass alloc] init];
[self.customClass method1];

Answer 2

It is easy enough using simply a Dictionary

 20> extension Dictionary {
 21.     func toJSONString () -> String { return "my dictionary" }
 22. }
 23> ["a": 1, "b": 2].toJSONString()
$R10: String = "my dictionary"

The Apple documentation does not mention using extensions on Objective-C classes.