iOS-使用協議和委托將資料從Swift傳遞到ObjCVC

我試圖在關閉時使用委托將資料從 Swift VC2 傳遞回 ObjC VC1，下面是我的代碼。

VC2（迅捷）

//protocol used for sending data back
@objc protocol DataEnteredDelegate: AnyObject {
    func userDidEnterInformation(info: String)
}

class VC2: UIViewController {

    weak var delegate: DataEnteredDelegate? = nil

    // **Go back to VC1**
    @IBAction func doneBtn(_ sender: Any) { 
      session.stop();
      delegate!.userDidEnterInformation(info: "sending date from Swift VC2")
      self.dismiss(animated: true, completion: nil) 
    }
}

VC1.m (objc)

#import "ProjectName-Swift.h"

@interface VC1 () <>
 
@end

@implementation VC1
// **Navigate to VC2**
-(void)goToVC2 {
    VC2 *vc2 = [[UIStoryboard storyboardWithName: @"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"VC2ID"];
    [self presentViewController: vc2 animated: YES completion: nil];
}
@end

VC1.h (objc)

@interface VC1 : UIViewController

@end

如何在移動到 VC2 之前在 VC1 中分配委托以及如何在 VC1 (objc) 檔案中實作協議，即 DataEnteredDelegate 和 func userDidEnterInformation。

我相信我已經完成了任務的快速部分，但正在尋找 Objc 實作。

uj5u.com熱心網友回復：

非常基本的例子...

假設我們在 Storyboard 中有：

• ObjcViewController帶有“Present It”按鈕的 Objective-C 控制器
• 一個SwiftViewController帶有“完成”按鈕的 Swift 控制器，帶有Identifier: "SwiftVC"

并且按鈕連接到IBAction方法...

ObjcViewController.h

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@interface ObjcViewController : UIViewController

@end

NS_ASSUME_NONNULL_END

物件視圖控制器.m

#import "ObjcViewController.h"

#import "YourProject-Swift.h"

@interface ObjcViewController () <DataEnteredDelegate>

@end

@implementation ObjcViewController

- (IBAction)goToSwiftVC:(id)sender {
    
    SwiftViewController *vc = (SwiftViewController *)[self.storyboard instantiateViewControllerWithIdentifier:@"SwiftVC"];
    [vc setMyDelegate:self];
    [self presentViewController:vc animated:YES completion:nil];
    
}

- (void)userDidEnterInformationWithInfo:(NSString * _Nonnull)info {
    NSLog(@"Delegate sent back: %@", info);
}

@end

SwiftViewController.swift

import UIKit

@objc public protocol DataEnteredDelegate {
    func userDidEnterInformation(info: String)
}

class SwiftViewController: UIViewController {

    @objc public var myDelegate: DataEnteredDelegate?
    
    @IBAction func doneBtn(_ sender: Any) {
        myDelegate?.userDidEnterInformation(info: "from SwiftVC")
        self.dismiss(animated: true, completion: nil)
    }

}

uj5u.com熱心網友回復：

首先，您需要使用 @objc 創建委托實體初始值

VC2（迅捷）

//protocol used for sending data back
@objc protocol DataEnteredDelegate: AnyObject {
    func userDidEnterInformation(info: String)
}

class VC2: UIViewController {

   @objc weak var delegate: DataEnteredDelegate?

    // **Go back to VC1**
    @IBAction func doneBtn(_ sender: Any) { 
      session.stop();
      delegate!.userDidEnterInformation(info: "sending date from Swift VC2")
      self.dismiss(animated: true, completion: nil) 
    }
} 

現在在objective-c，VC1.m（objc）

#import "ProjectName-Swift.h"

@interface VC1 () <DataEnteredDelegate>
 
@end

@implementation VC1
// **Navigate to VC2**
-(void)goToVC2 {
    VC2 *vc2 = [[UIStoryboard storyboardWithName: @"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"VC2ID"];
    [vc2 delegate:self];
    [self presentViewController: vc2 animated: YES completion: nil];
}

//On dismiss vc2 this delegate will call
- (void)userDidEnterInformationWithInfo:(NSString *)info{
    NSLog(@"%@", info);
}
@end

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