Swift Objective-C Interop

2. COMBINING SWIFT AND
OBJECTIVE-C

3. AGENDA
Using Objective-C from Swift
Using Swift from Objective-C
Objective-C Behavior in Swift Classes

4. IMPORTING OBJECTIVE-C
INTO SWIFT

5. APPLE FRAMEWORKS
No additional setup required!
import UIKit
import Foundation

6. OBJECTIVE-C WITHIN SAME TARGET
Add Objective-C files to the Bridging-Header
Bridging-Header needs to be referenced in
build settings
Project-
Bridging-
Header.h
A.swift B.swift
MyObj.h
Car.h
MyObj.m
Car.m

7. THIRD PARTY FRAMEWORKS
If framework is built as a module:
No additional setup required
import Parse

8. THIRD PARTY FRAMEWORKS
If framework is written in Obj-C
And framework is not built as a module
Add framework header to bridging-header:
#ifndef Makestagram_Makestagram_Bridging_Header_h
#define Makestagram_Makestagram_Bridging_Header_h
#import <Parse/Parse.h>
#endif

9. CALLING OBJECTIVE-C
FROM SWIFT

10. CALLING OBJ-C FROM SWIFT
Most syntax translates almost 1-1
Special rules for initializers

11. INITIALIZERS
[[UITableView alloc] initWithFrame:CGRectZero style:UITableViewStyleGrouped];
UITableView(frame: CGRectZero, style: .Grouped)
[UIColor colorWithRed:0.5 green:0.0 blue:0.5 alpha:1.0];
UIColor(red: 0.5, green: 0.0, blue: 0.5, alpha: 1.0)

12. METHODS
[myTableView insertSubview:mySubview atIndex:2];
myTableView.insertSubview(mySubview, atIndex: 2)

13. PROPERTIES
myTextField.textColor = UIColor.darkGrayColor()

14. OPTIONALITY IN OBJ-C
Since latest release of Objective-C we can
specify whether values can be nil or not
For unaudited APIs: Implicitly unwrapped
Optionals by default!

15. OPTIONALITY IN OBJ-C
// unaudited version -> generates warning
+ (UIView *)createViewWithName:(NSString *)name;
// return value and argument are non-optional
+ (__nonnull UIView *)createViewWithNameSwiftier:(__nonnull NSString *)name;
// return value and argument are optional
+ (__nullable UIView *)createViewWithNameSwiftierNullable:(__nullable NSString *)name;

16. USING SWIFT FROM
OBJECTIVE-C

17. SWIFT WITHIN SAME TARGET
AppName
-Swift.h
A.swift
B.swift
MyObj.h Car.h
MyObj.m Car.m

18. NSOBJECT SUBCLASSES
class SimpleNSObject: NSObject {
}
#import "InteropTest-Swift.h"
- (void)test {
SimpleNSObject *simple2 = [[SimpleNSObject alloc] init];
}

19. SWIFT ROOT CLASS
@objc public class Simple {
public class func newInstance() -> Simple {
return Simple()
}
}
#import "InteropTest-Swift.h"
- (void)test {
Simple *simple = [Simple newInstance];
}

20. OBJECTIVE-C BEHAVIOR IN
SWIFT CLASSES

21. OBJECTIVE-C BEHAVIOR IN
SWIFT CLASSES
class User {
dynamic var name: String
dynamic func setUp() {
//...
}
}
Use the dynamic keyword to enable Objective-C
features such as KVO and performSelector:

22. ADDITIONAL RESOURCES
Using Swift with Cocoa and Objective-C
(Apple)
Mike Ash Talk: Swift and C
Russ Bishop Talk: Unsafe Swift