I'm attempting to slowly migrate an Objective C app over to Swift and have started to create new classes -
public class MapsAPI : NSObject {
let delegate: MapsAPIResponseDelegate
public init(managerWithDelegate delegate: MapsAPIResponseDelegate) {
self.delegate = delegate
}
}
Now in my Objective C .m file I've declared #import MyTarget-Swift.h and in my .h I've added #class MapsAPI which all seems fine however I'm not sure what the Objective C initialisation code should look like. I've tried -
MapsAPI *api = [[MapsAPI alloc] initWithManagerWithDelegate: self];
But that errors with -
No visible #interface for 'MapsAPI' declares the selector
'initWithManagerWithDelegate:'
I've tried looking at the definition of my MyTarget-Swift.h but all that shows is -
SWIFT_CLASS("_TtC4What7MapsAPI")
#interface MapsAPI : NSObject
- (nonnull instancetype)init SWIFT_UNAVAILABLE;
#end
Is there something I'm doing wrong here?
You may choose to add #objcMembers to your class declaration:
public class #objcMembers MapsAPI : NSObject {
let delegate: MapsAPIResponseDelegate
public init(managerWithDelegate delegate: MapsAPIResponseDelegate) {
self.delegate = delegate
}
}
Alternatively (or additionally... who am I to judge) you can mark your initializer as being exposed to Objective-C
public class MapsAPI : NSObject {
let delegate: MapsAPIResponseDelegate
#objc public init(managerWithDelegate delegate: MapsAPIResponseDelegate) {
self.delegate = delegate
}
}
And if you want to, you can also explicitly define the Objective-C selector used:
public class MapsAPI : NSObject {
let delegate: MapsAPIResponseDelegate
#objc(initManagerWithDelegate:)
public init(managerWithDelegate delegate: MapsAPIResponseDelegate) {
self.delegate = delegate
}
}
Related
I am trying to get the Swift protocol to work in Objective-C file, but the application crashes when the error as below.
+[OpenCamera onCameraClose]: unrecognized selector sent to class 0x102ff8580
I am not sure as to what I am missing.
//Swift: UIViewController Code
#objc protocol CameraViewControllerDelegate {
func onCameraClose()
}
#objc class CameraViewController: UIViewController {
var delegate : CameraViewControllerDelegate? = nil
func closeCamera(sender: Any) {
delegate?.onCameraClose()
}
}
// Objective-C : UIViewController Code
OpenCamera.h
#interface OpenCamera : UIViewController <CameraViewControllerDelegate>
OpenCamera.m
#import <MyProjectName/MyProjectName-Swift.h>
#implementation OpenCamera
- (void)viewDidLoad {
[super viewDidLoad];
CameraViewController *cameraViewController = [[CameraViewController alloc] initWithNibName:#"CameraView" bundle:nil];
cameraViewController.delegate = self; //Warning - Incompatible pointer types assigning to 'id<CameraViewControllerDelegate> _Nullable' from 'Class'
}
- (void)onCameraClose {
NSLog(#"Swift Protocol method executed from Objective-C");
}
#end
The warning here did in fact predict the crash:
cameraViewController.delegate = self;
//Warning - Incompatible pointer types assigning to 'id<CameraViewControllerDelegate> _Nullable' from 'Class'
Clearly it thinks self is a class, not an instance. That's very odd.
My guess is that there is something wrong with your import arrangements, but you have not shown enough information to see what it is. I'll just show an arrangement that works.
Let's assume you have both Objective-C and Swift code in one target (i.e. that no frameworks are involved). Then in Swift, you say:
#objc protocol CameraViewControllerDelegate {
func onCameraClose()
}
class CameraViewController: UIViewController {
#objc var delegate : CameraViewControllerDelegate? = nil
func closeCamera(sender: Any) {
delegate?.onCameraClose()
}
}
Note the use of #objc var to expose the delegate property. There is no need to expose the class to Objective-C, as it is already an NSObject derivative.
Okay, in Objective-C, here is your interface file:
#import <UIKit/UIKit.h>
#interface OpenCamera : UIViewController
#end
Note that you do not import the generated header in a .h file, and you do not attempt to mention an imported protocol here.
On to the implementation file:
#import "OpenCamera.h"
#import "MyProject-Swift.h"
#interface OpenCamera () <CameraViewControllerDelegate>
#end
#implementation OpenCamera
- (void)viewDidLoad {
[super viewDidLoad];
CameraViewController *cameraViewController = [[CameraViewController alloc] initWithNibName:#"CameraView" bundle:nil];
cameraViewController.delegate = self;
}
- (void)onCameraClose {
NSLog(#"Swift Protocol method executed from Objective-C");
}
#end
We import the corresponding .h file and the generated header .h file here. We use an anonymous category to declare conformance to the protocol, and the rest is as you have it. You won't see any warnings.
I am using Objective-C to consume a Swift Code that I am turning into a Framework/SDK eventually.
I can not invoke the class Methods specifically to Objective-C, and I am getting this error
No visible #interface for 'class' declares the selector 'method'
Swift File
public class Example {
public class func testOne() -> NSString {
return "testOne";
}
public func testTwo() -> NSString {
return "testTwo";
}
}
Objective-C File
#import <ProjectModuleName-Swift.h>
#interface ...
#end
#implmentation ...
- (void) testing {
Example *example = [[Example alloc] init];
NSString *testOne = [example testOne]; // does not work ; No visible #interface for 'Example' declares the selector 'testOne'
NSString *testTwo = [example testTwo]; // does work
}
#end
Obviously, by declaring class func it should require a different way to invoke it through Objective-C, but I have not seen any docs on this topic.
An example or help would be much appreciated.
Class methods are called on the class, not instances of the class:
NSString *testOne = [Example testOne];
NSString *testTwo = [Example testTwo];
I have created on Class in Swift and that class and its protocol I am using in Obj-C enabled project but I am getting below error while compiling my project.
cannot find protocol declaration for 'SpeechRecognizerDelegate'; did
you mean 'SFSpeechRecognizerDelegate'?
Can anyone guide me on this how can I use Swift class protocol in my Obj-C class.
Here is my Swift code:
protocol SpeechRecognizerDelegate : class {
func speechRecognitionFinished(_ transcription:String)
func speechRecognitionError(_ error:Error)
}
class SpeechRecognizer: NSObject, SFSpeechRecognizerDelegate {
open weak var delegate: SpeechRecognizerDelegate?
}
Protocol use in Obj-C:
#import "ARBot-Swift.h"
#interface ChatScreenViewController : JSQMessagesViewController <SpeechRecognizerDelegate>
Let me know if required more info.
Thanks in Advance.
in Swift:
#objc public protocol YOURSwiftDelegate {
func viewReceiptPhoto()
func amountPicked(selected: Int)
}
class YourClass: NSObject {
weak var delegat: YOURSwiftDelegate?
}
in Objective-C headerFile.h
#protocol YOURSwiftDelegate;
#interface YOURController : UIViewController < YOURSwiftDelegate >
in Objective-C Implementation.m
SwiftObject * swiftObject = [SwiftObject alloc] init];
swiftObject.delegate = self
Define your Swift protocol like this inside your Swift file.
#objc protocol SpeechRecognizerDelegate: class{
func speechRecognitionFinished(_ transcription:String)
func speechRecognitionError(_ error:Error)
}
Create a Swift Module inside your project setting then use it. You can find here complete blog for the mix language coding.
Then use Protocol inside Objective C class,
We required to add protocol inside Objective C file -
#import "ARBot-Swift.h"
#interface ChatScreenViewController : JSQMessagesViewController <SpeechRecognizerDelegate>
Then you need to conform to the protocol methods -
- (void)viewDidLoad {
[super viewDidLoad];
SpeechRecognizer * speechRecognizer = [[SpeechRecognizer alloc] init];
speechRecognizer.delegate = self;
}
#pragma mark - Delegate Methods
-(void)speechRecognitionFinished:(NSString *) transcription{
//Do something here
}
-(void)speechRecognitionError:(NSError *) error{
//Do something here
}
I had a similar issue after following (import header + Objc annotation on protocol). I got the warning when using Swift code from Objective C headers. Solved by only importing into the implementation .m files.
Add #objc attribute to your protocol:
#objc protocol SpeechRecognizerDelegate : class {
//...
}
Include Swift Classes in Objective-C Headers Using Forward Declarations
//MySwiftClass.swift
#objc protocol MySwiftProtocol {}
#objcMembers class MySwiftClass {}
// MyObjcClass.h
#class MySwiftClass;
#protocol MySwiftProtocol;
#interface MyObjcClass : NSObject
- (MySwiftClass *)returnSwiftClassInstance;
- (id <MySwiftProtocol>)returnInstanceAdoptingSwiftProtocol;
// ...
#end
I have two files
Question.m
Question.h
These two are written by Objective-C
MainView.swift
This is written by Swift
Question Class has the delegate
#interface Question : NSObject{
id delegate;// put MainViewController here
- (void)trythisfunction{
[delegate test] // compiler doesn't find this method.
}
}
and I make class instance and put MainViewController as delegate of Question in MainViewController.swift
class MainViewController: UIViewController {
override func viewDidLoad(){
q = Question()
q.delegate = self // put self in delegate
}
func test(){
NSLog("test is OK")
}
}
However Compiler found error [delegate test]
Question.m:169:19: No known instance method for selector 'test:'
How can I solve this??
You need to make few changes.
Below class declaration doesn't compile because you can't declare variables inside interface.
#interface Question : NSObject{
id delegate;
- (void)trythisfunction {
[delegate test]
}
}
I have fixed above and the class now looks like this,
# Question.h file
#import <Foundation/Foundation.h>
#interface Question : NSObject
#property (nonatomic, strong) id delegate;
#end
Below is the implementation of the class
# Question.m file
#import "Question.h"
#implementation Question
#synthesize delegate;
- (void)trythisfunction{
[delegate test];
}
#end
As we are integrating this swift and so we will need a Bridging Header whose content look like.
#import "Test.h"
Finally in your swift class now you can import this class
import UIKit
class MainViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let q = Test()
q.delegate = self
}
func test(){
NSLog("test is OK")
}
}
And above code works like a charm.
I have a Objective C class that has methods that look like this:
#class Client;
#protocol ClientDelegate <NSObject>
#optional
-(void) receivedMessageFromClient : (id) message;
#end
#interface Client : NSObject
+(id) setup;
#property(nonatomic, strong) id <ClientDelegate> clientDelegate;
// more method declarations below
I am implementing the ClientDelegate in my Swift class like this:
class HomeViewController: UIViewController, ClientDelegate {
var client : AnyObject?
var delegate: ClientDelegate?
override func viewDidLoad() {
super.viewDidLoad()
client = Client.setup() as! Client
client.clientDelegate = self
}
func receivedMessageFromClient(message: AnyObject) {
print("Message recieved: \(message)")
}
}
This is giving me a compiling error:
Cannot assign to property: 'self' is immutable
When I remove the lines
client = Client.setup() as! Client
client.clientDelegate = self
the code compiles and calls the method in the Client class that in turns sends a message to receivedMessageFromClient, but the method is not called in HomeViewController. It seems that everything is setup with the exception of assigning self to be the delegate.
Check out my comments on your question but this is a basic example of an Objective-C delegate implemented in Swift:
Objective-C:
#protocol MyDelegate <NSObject>
#optional
- (void)canImplementThis:(int)aVar;
#required
- (BOOL)needToImplementThis;
#end
#interface MyClass : NSObject
#property (nonatomic, weak) id<MyDelegate> delegate;
#end
Swift:
class SwiftClass : UIViewController, MyDelegate {
var myObj : MyClass?
override func viewDidLoad() {
super.viewDidLoad()
myObj = MyClass()
myObj?.delegate = self
}
// MARK: - <MyDelegate>
func canImplementThis(aVar : Int) {
print("Called: \(aVar))
}
func needToImplementThis() -> Bool {
return false
}
}
Forgive any typos I typed this out straight into SO.
Had to change Int to Int32 for some reason so it fix the invalid selector issue, with Int32 on the swift side but then worked