If you do not know, and by now you should. Apple have created a whole new programming language called Swift. Do not fret you Objective-C Coders out there. This tutorial will show you how you can use Objective-C Classes in Swift.
We have an updated article on Swift Classes for Swift 2, If you’re interested.
Apple have some really good documentation here . So, If you have an existing class that you’d like to use, perform Step 2 and then skip to Step 5. For some cases, I had to add an explicit to an older Objective-C File:
#import
Step 1: Add Objective-C Implementation — .m
Add a .m file to your class, and name it CustomObject.m. If you need information on starting an iOS Application check out our: Create new Single View Application
Step 2: Add Bridging Header
When adding your .m file, you’ll likely be hit with a prompt that looks like the one below, Click Yes!:
For an explanation of how to create an Objective-C Bridging Header. Check out: How to create an Objective-C Bridging header
If you did not see the prompt, or accidentally deleted your bridging header, add a new .h file to your project and name it <#YourProjectName>-Bridging-Header.h
Step 3: Add Objective-C Header — .h
Add another .h file and name it CustomObject.h
Step 4: Build your Objective-C Class
In CustomObject.h
#import
@interface CustomObject : NSObject
@property (strong, nonatomic) id someProperty;
- (void) someMethod;
@end
In CustomObject.m
#import "CustomObject.h"
@implementation CustomObject : NSObject
- (void) someMethod {
NSLog(@"SomeMethod Ran");
}
@end
Step 5: Add Class to Bridging-Header
In YourProject-Bridging-Header.h:
#import "CustomObject.h"
Step 6: Use your Object
In SomeSwiftFile.swift:
var instanceOfCustomObject: CustomObject = CustomObject()
instanceOfCustomObject.someProperty = "Hello World"
println(instanceOfCustomObject.someProperty)
instanceOfCustomObject.someMethod()
No need to import explicitly, that’s what the bridging header is for.
Using Swift Classes in Objective-C
Follow these steps:
Step 1: Create New Swift Class
Add a .swift file to your project, and name it MySwiftObject.swift
In MySwiftObject.swift:
import Foundation
class MySwiftObject : NSObject {
var someProperty: AnyObject = "Some Initializer Val"
init() {}
func someFunction(someArg:AnyObject) -> String {
var returnVal = "You sent me \(someArg)"
return returnVal
}
}
Step 2: Import Swift Files to Objective-C Class
In SomeRandomClass.m:
#import "<#YourProjectName#>-Swift.h"
The file:<#YourProjectName#>-Swift.h should already be created automatically in your project, even if you can not see it.
Step 3: Use your class
MySwiftObject * myOb = [MySwiftObject new];
NSLog(@"MyOb.someProperty: %@", myOb.someProperty);
myOb.someProperty = @"Hello World";
NSLog(@"MyOb.someProperty: %@", myOb.someProperty);
NSString * retString = [myOb someFunction:@"Arg"];
NSLog(@"RetString: %@", retString);
Note: CodeCompletion wasn’t behaving as accurately as I’d like it to. On my system, running a quick build w/ “cmd + r” seemed to help Swift find some of the Objc code and vice versa.
This was a great article on StackOverflow.
