委托未調用協議方法

Question

我已經在我的應用中實現了協議，

我已經在loginViewController聲明了協議方法，並且我正在從confirmViewController調用protocolMethod

這是我的代碼段： loginViewController.h

@protocol FirstControllerDelegate<NSObject>
@required
-(void)protocolMethod;

@end

@interface loginViewController : UIViewController<FirstControllerDelegate>

@end

loginViewController.m

- (IBAction)loginBtnClicked:(id)sender {
    confirmViewController *obj = [confirmViewController new];
     obj.delegate=self;
   [self performSegueWithIdentifier:@"confirmloginsegue" sender:self];


}

-(void)protocolMethod{
    NSLog(@"--- This is not callled ---");
     [self dismissViewControllerAnimated:NO completion:nil];
}

用於confirmViewController.h代碼

@interface confirmViewController : UIViewController

@property (nonatomic, assign) id <FirstControllerDelegate> delegate;

@end

confirmViewController.m

 (IBAction)continueClicked:(id)sender {

    [_delegate protocolMethod]; //Calling protocol method...
    [self dismissViewControllerAnimated:YES completion:nil];
}

我在哪里做錯了？

請幫助並提前致謝！

Answer 1

錯誤的方法和委托初始化

在這行中：

confirmViewController *obj = [confirmViewController new];
     obj.delegate=self;
   [self performSegueWithIdentifier:@"confirmloginsegue" sender:self];    

--- You are loosing the object here

解

在屬性檢查器中，為該ConfirmViewController提供標識符，現在推送vc並設置對象ConfirmViewController的委托，如下所示：-

UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
ConfirmViewController *confirmViewController = [storyboard instantiateViewControllerWithIdentifier:@"ConfirmViewController"];

confirmViewController.delegate=self;

[self.navigationController pushViewController:confirmViewController animated:YES];

Answer 2

委托類的存在時間不足以引起關注：

- (IBAction)loginBtnClicked:(id)sender {
    confirmViewController *obj = [confirmViewController new];
    obj.delegate=self;
    [self performSegueWithIdentifier:@"confirmloginsegue" sender:self];
    // obj is destroyed here
}

Answer 3

您需要實現prepareForSegue並在那里設置delegate ，例如

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    confirmViewController *destViewController = (confirmViewController *)segue.destinationViewController;
    destViewController.delegate=self;
}

有關更多詳細信息，請檢查此鏈接：-http: //www.appcoda.com/storyboards-ios-tutorial-pass-data-between-view-controller-with-segue/

Answer 4

您必須在那里設置代表。 請在您的代碼中進行一些更正，例如：

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
confirmViewController *destViewController = (confirmViewController *)segue.destinationViewController;
destViewController.delegate=self;

}

Answer 5

您應該使用preparefrosegue設置您的委托對象。 所以你的代碼應該是這樣的，

- (IBAction)loginBtnClicked:(id)sender {

   [self performSegueWithIdentifier:@"confirmloginsegue" sender:self];
  }

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{

confirmViewController *obj = [confirmViewController new];

//or

confirmViewController *obj = [segue destinationViewController];

obj.delegate=self;
}

希望這會有所幫助;）

Answer 6

如果您正在使用View Controller

SettingsHubViewController *settingVC = [[UIStoryboard storyboardWithName:@"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"yourStoryBoardIdentifier"];

settingVC.delegate = self;

如果您正在使用XIB，則在設置settingVC.delegate = self;之后加載NIB settingVC.delegate = self;

它為我工作（我創建了OverLay視圖並加載到主類中）